A Fault Detection Method for Automatic Detection of Spawning in Oysters

Using measurements of valve activity (i.e., the distance between the two valves) in populations of bivalves under natural environmental conditions (16 oysters in the Bay of Arcachon, France, in 2007, 2013, and 2014), an algorithm for an automatic detection of the spawning period of oysters is proposed in this brief. Spawning observations are important in aquaculture and biological studies, and until now, such a detection is done through visual analysis by an expert. The algorithm is based on the fault detection approach and it works through the estimation of velocity of valve movement activity, which can be obtained by calculating the time derivative of the valve distance. A summarized description of the methods used for the derivative estimation is provided, followed by the associated signal processing and decision-making algorithm to determine spawning from the velocity signal. A protection from false spawning detection is also considered by analyzing the simultaneity in spawning. Through this study, it is shown that spawning in a population of oysters living in their natural habitat (i.e., in the sea) can be automatically detected without any human expertise, saving time and resources. The fault detection method presented in this brief can also be used to detect complex oscillatory behavior which is of interest to control engineering community.<br/

Monitoring biological rhythms through the dynamic model identification of an oyster population

International audienceThe measurements of valve activity in a population of bivalves under natural environmental conditions (16 oysters in the Bay of Arcachon, France) are used for a physiological model identification. A nonlinear auto-regressive exogenous (NARX) model is designed and tested. The method to design the model has two parts. 1) Structure of the model: The model takes into account the influence of environmental conditions using measurements of the sunlight intensity, the moonlight, tide levels, precipitation and water salinity levels. A possible influence of the internal circadian/circatidal clocks is also analyzed. 2) Least square calculation of the model parameters. Through this study, it is demonstrated that the developed dynamical model of the oyster valve movement can be used for estimating normal physiological rhythms of permanently immersed oysters and can be considered for detecting perturbations of these rhythms due to changes in the water quality, i.e. for ecological monitoring

Robust Intrusion Detection for Resilience Enhancement of Industrial Control Systems: An Extended State Observer Approach

We address the problem of attack signal estimation in industrial control systems that are subjected to actuator false data injection attack (FDIA) and where the sensor measurements are corrupted by non-negligible high-frequency measurement noise. The actuator FDIA signal is categorized as disturbance to be estimated and subsequently compensated, based on the concept of extended state observer (ESO). We investigate the efficacy of two alternatives to conventional ESO namely, cascade ESO (CESO) and low-power higher-order ESO (LHESO), that guarantee improved estimation performance in case of noisy measurement data as well as time-varying attack signals. Simu-lation and experimental results under different types of FDIAs demonstrate the advantages of designed schemes in comparison to conventional linear and nonlinear ESOs, using network motion control system as an illustrative example. The results highlight the limitations of conventional ESO under noisy measurement data, particularly nonlinear ESO which is based on fal(·) function and commonly used in control literature

Increasing Sustainable Bivalve Aquaculture Productivity Using Remote Non-Invasive Sensing and Upweller Technologies

The work and findings described by this thesis aim to develop technologies and approaches relevant to bivalve aquaculture, focusing on non invasive sensing to monitor bivalve shellfish, primarily the Pacific oyster (Magallana gigas). Following the introduction, Chapter 2 presents an overview of the Non Invasive Oyster Sensor (NOSy), a sensor developed at the University of Essex that records bivalve openness (gape). NOSy was conceived to automatically detect spawning as an aid to oyster growers and has proved useful in field and laboratory, work which underpins three chapters in this thesis. NOSy remains under development, and has potential for use in aquaculture, monitoring and research. Chapter 3 assesses the role of salinity in driving estuarine oyster behaviour. We replicated an estuarine tidal salinity cycle and recorded the gape of oysters exposed to it. Behaviours during the experiment did not resemble those in the estuary, suggesting that salinity alone does not drive estuarine oyster behaviour. We also discuss the challenges of controlling salinity in a laboratory, and suggest it is an under-studied area. Chapter 4 discusses land based systems for young oyster growing. Land-based systems have the potential to improve growth, condition and survival while reducing labour and maintenance costs. We trialled a system over three summers, with promising results. Reduction of localised densities improved growth rate and uniformity. Cost forecasts suggest that adoption of land based growing systems could result in substantial savings. Chapter 5 presents gaping records from an area where Blue mussels (Mytilus edulis) have become non harvestable in recent years due to contamination. We used NOSy to assess gaping patterns of the mussel population to evaluate how their behaviours affect their vulnerability to contamination. Mussels in the bay closed over low tide as a response to extremely low salinity, inferring protection from contamination by limiting the mussel’s exposure

Gaping behaviour of Blue mussels (Mytilus edulis) in relation to freshwater runoff risks

Shellfish grown for food are vulnerable to environmental contamination, potentially rendering them unsafe for human consumption. Non-invasive gape (valve openness) sensing allows in-situ monitoring of bivalve shellfish behaviours, such as feeding, that can result in exposure to contaminated waters. Sensors were attached to Blue mussels and deployed for 10 days on natural mussel beds in Dundrum Bay, Northern Ireland. Data showed a tidally synchronous behaviour pattern of high openness at high water and vice versa. It is likely that this is, at least in part, due to extreme salinity variation (1.8–33.6) resulting from near total water exchange with each tide in the bay. This behaviour is likely to infer a degree of protection from contaminants during periods of low water, a time at which runoff-derived pollutants are most concentrated

Gaping behaviour of Blue mussels (Mytilus edulis) in relation to freshwater runoff risks

Shellfish grown for food are vulnerable to environmental contamination, potentially rendering them unsafe for human consumption. Non-invasive gape (valve openness) sensing allows in-situ monitoring of bivalve shellfish behaviours, such as feeding, that can result in exposure to contaminated waters. Sensors were attached to Blue mussels and deployed for 10 days on natural mussel beds in Dundrum Bay, Northern Ireland. Data showed a tidally synchronous behaviour pattern of high openness at high water and vice versa. It is likely that this is, at least in part, due to extreme salinity variation (1.8–33.6) resulting from near total water exchange with each tide in the bay. This behaviour is likely to infer a degree of protection from contaminants during periods of low water, a time at which runoff-derived pollutants are most concentrated

Nuclear Power

The world of the twenty first century is an energy consuming society. Due to increasing population and living standards, each year the world requires more energy and new efficient systems for delivering it. Furthermore, the new systems must be inherently safe and environmentally benign. These realities of today's world are among the reasons that lead to serious interest in deploying nuclear power as a sustainable energy source. Today's nuclear reactors are safe and highly efficient energy systems that offer electricity and a multitude of co-generation energy products ranging from potable water to heat for industrial applications. The goal of the book is to show the current state-of-the-art in the covered technical areas as well as to demonstrate how general engineering principles and methods can be applied to nuclear power systems

2007/2008 Annual Report

Report year ends June 30

Fish behavior and its use in the capture and culture of fishes

Fishery management, Behaviour, Food fish, Fish culture, Conferences