Reducing herbicide discharge to sensitive environments using membrane bioreactors

A hybrid MBR/UV/GAC treatment system was researched to remove Ametryn, which is a commonly used herbicide in Australian farmlands, from wastewater. The research revealed that the hybrid system could be successfully used for 100% removal of Ametryn. Two mathematical models were developed to predict the frequency of chemical cleaning of MBR-membrane and the mechanism of fouling of membrane.

A marginalised Markov Chain Monte Carlo approach for model based analysis of EEG data

The work presented in this paper focuses on fitting of a neural mass model to EEG data. Neurophysiology inspired mathematical models were developed for simulating brain's electrical activity imaged through Electroencephalography (EEG) more than three decades ago. At the present well informative models which even describe the functional integration of cortical regions also exists. However, a very limited amount of work is reported in literature on the subject of model fitting to actual EEG data. Here, we present a Bayesian approach for parameter estimation of the EEG model via a marginalized Markov Chain Monte Carlo (MCMC) approach.

International business cycles and remittance flows

In this paper, we study the macroeconomic determinants of remittance flows. We place particular attention to fluctuations in remittance flows over the international business cycles. Estimating a dynamic panel data model using the system-GMM method over the period 1970–2007, we document that remittance inflows decrease with home country volatility. Contrarily, remittance inflows increase with the volatility in host countries, especially for middle-income countries. Lower interest rates in host countries lead to larger remittance outflows. Trade and capital account openness are the most important factors that determine both remittance inflows and outflows. We conclude that macroeconomic factors of both home and host countries are important for understanding remittance flows.

DDoS attack detection at local area networks using information theoretical metrics

DDoS attacks are one of the major threats to Internet services. Sophisticated hackers are mimicking the features of legitimate network events, such as flash crowds, to fly under the radar. This poses great challenges to detect DDoS attacks. In this paper, we propose an attack feature independent DDoS flooding attack detection method at local area networks. We employ flow entropy on local area network routers to supervise the network traffic and raise potential DDoS flooding attack alarms when the flow entropy drops significantly in a short period of time. Furthermore, information distance is employed to differentiate DDoS attacks from flash crowds. In general, the attack traffic of one DDoS flooding attack session is generated by many bots from one botnet, and all of these bots are executing the same attack program. As a result, the similarity among attack traffic should higher than that among flash crowds, which are generated by many random users. Mathematical models have been established for the proposed detection strategies. Analysis based on the models indicates that the proposed methods can raise the alarm for potential DDoS flooding attacks and can differentiate DDoS flooding attacks from flash crowds with conditions. The extensive experiments and simulations confirmed the effectiveness of our proposed detection strategies.

Evaluation of pre-treatments for minimizing membrane fouling in water recovery

 RO membrane major foulants were reviewed. Among available pre-treatment technologies four pre-treatments namely; MF, UF, MBR membranes and GMF are qualitatively ranked as best. Further, experiments and fouling mathematical models showed suitability of UF and MF membrane as pre-treatments, based on their higher permeability and lower fouling potentiality than others.

Habitat classification of temperate marine macroalgal communities using bathymetric LiDAR

Here, we evaluated the potential of using bathymetric Light Detection and Ranging (LiDAR) to characterise shallow water (<30 m) benthic habitats of high energy subtidal coastal environments. Habitat classification, quantifying benthic substrata and macroalgal communities, was achieved in this study with the application of LiDAR and underwater video groundtruth data using automated classification techniques. Bathymetry and reflectance datasets were used to produce secondary terrain derivative surfaces (e.g., rugosity, aspect) that were assumed to influence benthic patterns observed. An automated decision tree classification approach using the Quick Unbiased Efficient Statistical Tree (QUEST) was applied to produce substrata, biological and canopy structure habitat maps of the study area. Error assessment indicated that habitat maps produced were primarily accurate (>70%), with varying results for the classification of individual habitat classes; for instance, producer accuracy for mixed brown algae and sediment substrata, was 74% and 93%, respectively. LiDAR was also successful for differentiating canopy structure of macroalgae communities (i.e., canopy structure classification), such as canopy forming kelp versus erect fine branching algae. In conclusion, habitat characterisation using bathymetric LiDAR provides a unique potential to collect baseline information about biological assemblages and, hence, potential reef connectivity over large areas beyond the range of direct observation. This research contributes a new perspective for assessing the structure of subtidal coastal ecosystems, providing a novel tool for the research and management of such highly dynamic marine environments. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

The effective radius and resistance to slippage

This work reveals that parallel gripper flat-jaw configuration affects grasping effectiveness. An important finding is the fact that object grasp reliability is influenced significantly by gripper's ability to develop high resistance to object rotation in the gripper. The concept of effective torque radius, which increases resistance to object rotation in the gripper, is presented here and can be extrapolated to other grasping devices and grasping strategies to improve their reliability and make them more effective. Grippers with full-jaw contact surface and those with discrete contact areas have been investigated using simple experimental setups. Essential mathematical models needed for analytical investigation, based on simple mechanics for full-jaw contact surfaces and discrete-jaw contact surfaces, are presented. These may be useful for gripper jaw design purposes.

What determines the yen swap spread?

We investigate if Japanese yen denominated interest rate swap spreads price risks in addition to liquidity and default risk. These additional risks include: the time-varying correlation between interest rates of different types and maturities; business cycle risk; and market skewness risk. Our analysis, over a number of different maturities and sample periods, supports the existence of an additional risk premium. We also show that the time-varying correlation between short term market interest rates (e.g., TIBOR) and the longer term Government bond yield (e.g., Gensaki) is of particular importance. Japanese yen swap spreads are shown to contain both pro-cyclical and counter-cyclical elements of business cycle risk, positive risk premia for skewness risk and variable risk premia for correlation risk (between fixed and floating interest rates).

Political connection and cost of debt: Some Malaysian evidence

This paper investigates the association between Malaysian politically connected (PCON) firms and the cost of debt. We extend previous research that finds Malaysian PCON firms are perceived as being of higher risk by the market, and by audit firms, by providing evidence that lenders also perceive these firms as being of higher risk. We also find that PCON firms have a significantly (1) higher extent of leverage, (2) higher likelihood of reporting a loss, (3) higher likelihood of having negative equity, and (4) higher likelihood of being audited by a big audit firm. We suggest that PCON firms are charged higher interest rates by lenders as a result of efficient contracting given their higher inherent risks. Additionally, we find that CEO duality present in PCON firms is perceived by lenders as being more risky, and that a higher proportion of independent directors on the audit committee mitigate this perceived risk. © 2012.

Counter-credit-risk yield spreads: a puzzle in China's corporate bond market

In this paper, using China's risk-free and corporate zero yields together with aggregate credit risk measures and various control variables from 2006 to 2013, we document a puzzle of counter-credit-risk corporate yield spreads. We interpret this puzzle as a symptom of the immaturity of China's credit bond market, which reveals a distorted pricing mechanism latent in the fundamental of this market. We also find interesting results about relationships between corporate yield spreads and interest rates and risk premia and the stock index, and these results are somewhat attributed to this puzzle.

Robust optimal motion cueing algorithm based on the linear quadratic regulator method and a genetic algorithm

The aim of this paper is to design and develop an optimal motion cueing algorithm (MCA) based on the genetic algorithm (GA) that can generate high-fidelity motions within the motion simulator's physical limitations. Both, angular velocity and linear acceleration are adopted as the inputs to the MCA for producing the higher order optimal washout filter. The linear quadratic regulator (LQR) method is used to constrain the human perception error between the real and simulated driving tasks. To develop the optimal MCA, the latest mathematical models of the vestibular system and simulator motion are taken into account. A reference frame with the center of rotation at the driver's head to eliminate false motion cues caused by rotation of the simulator to the translational motion of the driver's head as well as to reduce the workspace displacement is employed. To improve the developed LQR-based optimal MCA, a new strategy based on optimal control theory and the GA is devised. The objective is to reproduce a signal that can follow closely the reference signal and avoid false motion cues by adjusting the parameters from the obtained LQR-based optimal washout filter. This is achieved by taking a series of factors into account, which include the vestibular sensation error between the real and simulated cases, the main dynamic limitations, the human threshold limiter in tilt coordination, the cross correlation coefficient, and the human sensation error fluctuation. It is worth pointing out that other related investigations in the literature normally do not consider the effects of these factors. The proposed optimized MCA based on the GA is implemented using the MATLAB/Simulink software. The results show the effectiveness of the proposed GA-based method in enhancing human sensation, maximizing the reference shape tracking, and reducing the workspace usage.

On Real-Time Monitoring And Control For Efficient Management Of Drinking Water Networks: Barcelona Case Study

Drinking water utilities in urban areas are focused on finding smart solutions facing new challenges in their real-time operation because of limited water resources, intensive energy requirements, a growing population, a costly and ageing infrastructure, increasingly stringent regulations, and increased attention towards the environmental impact of water use. Such challenges force water managers to monitor and control not only water supply and distribution, but also consumer demand. This paper presents and discusses novel methodologies and procedures towards an integrated water resource management system based on advanced ICT technologies of automation and telecommunications for largely improving the efficiency of drinking water networks (DWN) in terms of water use, energy consumption, water loss minimization, and water quality guarantees. In particular, the paper addresses the first results of the European project EFFINET (FP7-ICT2011-8-318556) devoted to the monitoring and control of the DWN in Barcelona (Spain). Results are split in two levels according to different management objectives: (i) the monitoring level is concerned with all the aspects involved in the observation of the current state of a system and the detection/diagnosis of abnormal situations. It is achieved through sensors and communications technology, together with mathematical models; (ii) the control level is concerned with computing the best suitable and admissible control strategies for network actuators as to optimize a given set of operational goals related to the performance of the overall system. This level covers the network control (optimal management of water and energy) and the demand management (smart metering, efficient supply). The consideration of the Barcelona DWN as the case study will allow to prove the general applicability of the proposed integrated ICT solutions and their effectiveness in the management of DWN, with considerable savings of electricity costs and reduced water loss while ensuring the high European standards of water quality to citizens.

Desenvolvimento de um programa de simulação computacional de sistemas de aquecimento solar para água

Esta Tese apresenta uma análise do comportamento térmico de um sistema de aquecimento solar operando por termossifão. Neste tipo de sistema o fluido no coletor solar é circulado por convecção natural, que acontece devido à diferença de massa específica da água ao longo circuito. Nestes sistemas a vazão mássica varia ao longo do dia e do ano, dependendo, dentre outros fatores, da irradiância solar absorvida, do perfil de temperaturas da água no sistema, da geometria, do volume e do perfil de demanda de água quente. Para uma avaliação detalhada do comportamento térmico de aquecedores solares operando por termossifão foram realizados ensaios experimentais e cálculos teóricos. Os resultados dos experimentos concordaram com aqueles apresentados na literatura e sua análise fundamentou o desenvolvimento do aplicativo TermoSim, um programa de simulação computacional do comportamento térmico de sistemas de aquecimento de água com energia solar. O tratamento matemático adotado no TermoSim compreende a modelagem dos coletores solares de acordo com a teoria de Hottel-Bliss-Whillier. O reservatório térmico é modelado com estratificação térmica, convecção e condução entre as camadas. A vazão mássica é obtida a partir do balanço da quantidade de movimento no circuito. Os modelos matemáticos empregados na construção do aplicativo TermoSim foram validados através do confronto dos resultados simulados com medidas experimentais. Foi demonstrado que a utilização destes modelos é adequada e permite reproduzir com precisão o comportamento térmico dos coletores solares e do reservatório térmico. Além do programa TermoSim, foi também desenvolvido o programa TermoDim, que é uma ferramenta para o dimensionamento de sistemas de aquecimento solar, que requer apenas o conhecimento dos parâmetros geométricos do sistema, dados meteorológicos em média mensal e informação a respeito do volume de demanda. O TermoDim é apropriado para estimar o desempenho de aquecedores solares operando por termossifão com tanques verticais e horizontais. O método de dimensionamento do TermoDim é baseado na correlação para a eficiência média mensal obtida neste trabalho a partir de um grande número de simulações.

The trasition from fixed to floating exchange rate regimes: the case of Brazil

This dissertation evaluates macroeconomic management in Brazil from 1994 to the present, with particular focus on exchange rate policy. It points out that while Brazil's Real Plan succeeded in halting the hyperinflation that had reached more than 2000 percent in 1993, it also caused significant real appreciation of the exchange rate situation that was only made worse by the extremely high interest rates and ensuing bout of severe financial crises in the intemational arena. By the end of 1998, the accumulation of internai and externai imbalances led the authorities to drop foreign exchange controls and allow the currency to float. In spite of some initial scepticism, the flexible rate regime cum inflation target proved to work well. Inflation was kept under control; the current account position improved significantly, real interest rates fell and GDP growth resumed. Thus, while great challenges still lie ahead, the recent successes bestow some optimism on the well functioning of this exchange rate regime. The Brazilian case suggests that successful transition from one foreign exchange system to another, particularly during financial crisis, does not depend only on one variable be it fiscal or monetary. In reality, it depends on whole set of co-ordinated policies aimed at resuming price stability with as little exchange rate and output volatility as possible.