Michael Belmont

University of Exeter | UoE · College of Engineering, Mathematics and Physical Sciences

Launch, recovery, and deck handling operational performance on smaller ship platforms like Corvettes, Frigates and Destroyers are qualified as the most challenging tasks in the UAS ship-deployment of a VTOL Uncrewed Air System (UAS). One of the main hurdles is the random nature of seaway-created deck motions coupled with ship structure disturbed ai...

Quiescent Period Prediction (QPP) purpose is to provide ship motion conditions and motion predictions with sufficient forecasted time to launch, recover, and complete other motion sensitive tasks regardless of the seaway. QPP operates within a federated architecture system containing measurement instruments such as a Wave Radar system used to map r...

Quiescent Period Prediction (QPP) purpose is to provide ship motion conditions and motion predictions with sufficient forecasted time to launch, recover, and complete other motion sensitive tasks regardless of the seaway. QPP operates within a federated architecture system containing measurement instruments such as a Wave Radar system used to map r...

One of the most challenging tasks in the deployment of ship-based manned and unmanned VTOL aviation is the launch and recovery and deck handling operational performance on smaller ship platforms. The same may be said of ship Well-deck-based surface boats, like Rhib and LCACs. Awareness and prediction of the ship’s position and movement in the ocean...

This report demonstrates the capability of the forward prediction of the properties of the arriving wind at a vessel for time intervals adequate to significantly aid in the recovery of a wide range of air vehicles onto vessels. For craft with flight decks sited in the fore part of the vessel it is adequate to simply predict the arriving wind. For t...

Conventional X-band radars constitute a convenient cheap source of measurements for deterministic sea wave profiling and prediction. The radar backscatter measurements, however, suffer from several imperfections such as the effects of larger waves shadowing smaller waves. In order to extract the wave profiles and build a reliable (spectral) sea mod...

A very simple non-linear operator technique is introduced for creating localised extreme wave events from underlying linear sea wave models. Both maximal and sub-maximal extreme events can be generated. The technique for generating extreme waves is intended as the basis of a practical tool for marine engineers; however it does reflect the effect s...

A simple nonlinear phase operator was recently introduced which when applied to standard sea wave models was able to generate many of the properties of extreme waves. This technique was not able to describe the largest events observed. The methodology is extended to include a second nonlinear operator which transfers part or all of the energy from...

Many maritime operations can benefit from short-term deterministic sea wave prediction (DSWP). Conventional X-band radars constitute a convenient cheap source of measurements for DSWP. The radar backscatter measurements suffer from several imperfections such as the effect of larger waves shadowing smaller waves. In order to extract the wave profile...

Many maritime operations can benefit from short-term deterministic sea wave prediction (DSWP). Conventional X-band radars constitute a convenient cheap source of measurements for DSWP. The radar backscatter measurements suffer from several imperfections such as the effect of larger waves shadowing smaller waves. In order to extract the wave profile...

Short-term deterministic sea wave prediction (DSWP) can facilitate the safe implementation of a number of maritime operations. Wave profile radars, based on the conventional X-band radars, have recently been proven to provide a low-cost convenient source of two-dimensional wave measurement for DSWP. The Golden Arrow sea trial in the North Atlantic...

A fundamental property of most sea conditions is that sets of large waves alternate with sets of smaller waves, known as quiescent periods. Exploiting the quiescent periods can expand the sea states under which the execution of many maritime operations can be considered safe. Building upon the work of Belmont et al., we extend the methodology to fu...

Understanding the effect of tidal turbines on local erosion of the estuarine bed is crucial for design and maintenance of turbines with stable foundations and assessment of their environmental impacts. This report describes the results of flume experiments on clear-water scour caused by a single cross-flow turbine in steady flow conditions. The tur...

A number of maritime operations can benefit from a short-term deterministic sea wave prediction (DSWP). Conventional X-band radars have recently been shown to provide a low-cost convenient source of two-dimensional wave profile information for DSWP purposes. However, such rotating radars typically introduce temporal smearing into the data, which in...

There is a growing practical interest in the ability to increase the sea states at which marine operations can be safely undertaken by exploiting the quiescent periods that are well known to exist under a wide range of sea conditions. While the actual prediction of quiescent periods at sea for the control of operations is a deterministic process th...

As commercial scale tidal energy devices are shortly to be deployed in the first arrays, the knowledge of how different array layouts perform is a key and under-examined field. Here, the Momentum Reversal Lift (MRL) turbine, developed by the University of Exeter, is deployed in five different array layouts utilising up to 15 devices. The use of dyn...

One key factor in the exploitation of tidal energy is the study of interactions of turbines when working in tidal turbine farms. The Momentum Reversal and Lift (MRL) turbine is a novel cross flow turbine. The three blades rotate around a common central horizontal axis which is parallel to their own axis and perpendicular to the flow. The novelty of...

Next generation turbines can be installed to exploit tidal energy resource in estuaries. However, the ecological implications of such deployments remain unknown. Accordingly, this study is focused on the impact of tidal farms on intertidal areas and associated waterbird habitats in estuaries. A numerical model simulates the hydrodynamic conditions...

Marine currents have been identified as a considerable renewable energy source. Therefore, in recent years, research on optimising tidal stream farm layouts in order to maximise power output has emerged. Traditionally, computational fluid dynamics (CFD) models are used to model power output, but their computational cost is prohibitive within an opt...

This paper investigates the accuracy of the Computational Fluid Dynamics (CFD) based Immersed Body Force (IBF) turbine modelling method for predicting the flow characteristics of a Momentum-Reversal-Lift type of tidal turbine. This empirically-based CFD model has been developed based on the actuator disc method enhanced with additional features to...

This paper investigates the influence of wake interaction and blockage on the performance of individual turbines in a staggered configuration in a tidal stream farm using the CFD based Immersed Body Force turbine modelling method. The inflow condition to each turbine is unknown in advance making it difficult to apply the correct loading to individu...

This paper investigates model predictive control (MPC) of a single sea wave energy converter (WEC). By using control schemes which constrain certain quantities, such as the maximum size of the feedback force, the energy storage for actuators and relative heave motion, it is possible for control to not only improve performance but to directly impact...

This paper addresses model predictive control (MPC) of highly-coupled clusters of sea wave energy converters (WECs). Since each WEC is not only a wave absorber but also a wave generator, the motion of each WEC can be affected by the waves generated by its adjacent WECs when they are close to each other. A distributed MPC strategy is developed to ma...

For a number of maritime tasks there is a short time period, typically only a few tens of seconds, where a critical event occurs that defines a limiting wave height for the whole operation. Examples are the recovery of fixed and rotary winged aircraft, cargo transfers, final pipe mating in fluid transfer operations, and launch/recovery of small cra...

Simulation technology has been used effectively and extensively across many NATO nations over the past 10 years to measure performance and support the management and reduction of risk across a wide range of ship acquisition projects. Clear emphasis is being placed on managing and reducing project risks, particularly during the design stages, to min...

This paper investigates model predictive control (MPC) of a sea wave energy converter(WEC). A novel objective function is adopted in the MPC design, which brings obvious benefits: First, the quadratic program (QP) derived from this objective function can be easily convexified, which facilitates the employment of existing efficient optimization algo...

Prediction of turbine-to-turbine interaction represents a significant challenge in determining the optimized power output from a tidal stream farm, and this is an active research area. This paper presents a detailed work which examines the influence of surrounding turbines on the performance of a base case (isolated turbine). The study was conducte...

This paper introduces a new CFD based Immersed Body Force (IBF) model, and examines the performance of a new type of tidal turbine, the Momentum Reversal Lift (MRL) turbine, developed by Aquascientific Ltd using the open source computational fluid dynamics (CFD) code OpenFOAM. The IBF model was added as a forcing function into the existing large ed...

Simulation technology has been used effectively and extensively across many NATO nations over the past 10 years to measure performance and support the management and reduction of risk across a wide range of ship acquisition projects. Clear emphasis is being placed on managing and reducing project risks, particularly during the design stages, to min...

We demonstrate that deterministic sea wave prediction (DSWP) combined with constrained optimal control can dramatically improve the efficiency of sea wave energy converters (WECs), while maintaining their safe operation. We focus on a point absorber WEC employing a hydraulic/electric power take-off system. Maximizing energy take-off while minimizin...

The interest of tidal energy exploitation is increasing in recent years promoting the need for development of efficient tidal turbines. This paper investigates the wake states of energy extraction by a new tidal turbine design, the Momentum Reversal Lift (MRL), developed by Aquascientific Ltd with a different method of tidal turbine modelling (body...

This paper investigates the sensitivity of width proximity and mesh grid size to the wake characteristics of Momentum Reversal Lift (MRL) turbine using a new computational fluid dynamics (CFD) based Immersed Body Force (IBF) model. This model has been added as a source term into the large eddy simulation (LES), which is developed for solving two ph...

Shallow-angle lidar offers an attractive approach to acquiring spatial profiles of sea waves, which are of value in both oceanographic research and practical engineering applications, such as in the control of wave energy capture devices and for a variety of vessel operations. However, the wave elevation values produced by shallow-angle lidar are i...

Early in the development of the new discipline of short term deterministic sea wave prediction (DSWP) the prediction region diagram was introduced. This was intended to provide information on the region in space and time where a propagating wave system arose from waves that had been previously totally measured. This diagram is compared here with a...

The potential of controlling wave energy converters, (WEC), by deterministic prediction of large damaging waves is introduced and shown to offer very substantial increases in the annual average power output of such devices. Results obtained for idealised WEC models show that the potential exists for this increase to be at least a factor of two. Num...

The principle of quiescent period prediction control (QPPC) is introduced in the context of sea wave energy capture (WEC) devices. The QPPC strategy is compared to approaches using statistical wave parameters for adaptive control of WECs and is shown to offer considerable increases in the average power captured. Assessing the quantitative benefits...

The UK government has committed to a reduction of carbon dioxide emissions for England and Wales by 20% below 1990 levels by 2010 and to increase the amount of electrical energy generated by renewable energy sources to 10% by 2010 and 15% by 2015. Wave and tidal energy are likely to contribute significantly to achieving these targets as important r...

This work presents an analytical study of the thermally activated amorphous-to-crystalline phase-change process when the heating source has a delta function temporal profile. This simulates the case of ultrafast heating where crystallization in the amorphous phase-change medium occurs during cooling. The study produced closed-form expressions that...

The problem discussed is the significance of anisotropies in the thermal parameters of different phases of phase-change materials as used for data storage purposes during recording. The particular phase change in interest is from the amorphous-to-crystalline state. Applying the method of correlation moment analysis produced upper estimators for the...

A LIDAR scanning system is described which is primarily designed to measure sea wave shape. The device is capable of measuring real-time spatial profiles over distances of hundreds of metres and as the LIDAR must inevitably operate from modest elevations, eg., from a vessels mast head it is inherently a very shallow angle metrology device. This res...

Vessel mounted shallow angle LIDAR makes it possible to measure the profile of sea waves at distances up to 1 km remote from the craft on which the instrument is mounted which enables a whole range of novel marine applications. However, the spatial sample locations at which the wave profiles are measured are highly non-uniformly distributed in spac...

Deterministic sea-wave prediction (DSWP) models are appearing in the literature designed for quiescent interval prediction in marine applications dominated by large swell seas. The approach has focused upon spectral methods which are straightforward and intuitively attractive. However, such methods have the disadvantage that while the sea is aperio...

The work presented introduces correlation moment analysis. This technique can be employed to explore the growth of determinism from stochastic initial conditions in physical systems described by non-linear partial differential equations (PDEs) and is also applicable to wholly deterministic situations. Correlation moment analysis allows the analytic...

The Exeter University Marine Dynamics Group has developed a shallow angle LIDAR for wave measurement purposes. This paper introduces the system and illustrates some metrology issues specific to this method. The LIDAR system uses a 532 nm (green) Q switched, high repetition rate, nanosecond pulsed laser. The system is designed to be scanned along a...

Simulations of deterministic sea wave prediction provide empirical evidence of the dependence of prediction accuracy on the degree of statistical dependence present in wave models. This issue is examined and to arise from the effect of local coherence on the estimation of spectral coefficients used in prediction models. Coherence within the phase s...

Short term deterministic sea wave prediction (DSWP) offers the promise of considerably extending the operational envelope of many marine activities such as aircraft launch and recovery onto vessels, cargo transfers, station-keeping roles and shuttle tanker activities. A short term prediction model first builds a description of the local sea surface...

A hybrid phase measuring system is described which is an adaptive development of traditional phase locked loops. It is based around a digital delay line. The target application is a slope-measuring continuous wave lidar designed to determine surface profiles at shallow angles of incidence. The lidar unit, of which the phase shifter is a key element...

A new alternative to cross-correlation is examined which forms the basis for developing analogue hardware systems designed to operate in the GHz range, beyond the point where digital spectral methods are realistic. The methodology is designed to realise the time resolution and noise rejection capabilities of wideband modulation by chirps, PRBS or w...

Statistical dependence within the phase spectrum of simulated swell seas are examined in terms its effect upon the precision of short term deterministic wave prediction models. Numerical experiments show that such local coherence increases the prediction accuracy. Analytic models are developed of the prediction which explain the sensitivity of the...

A simple dielectric motor has been developed in which the driving torque is derived by interaction of the interelectrode field with charge deposited on the rotor surface from the semi-insulating liquid ambient. Optimization of the torque has been effected by using a multi-electrode structure, and by shaping of the electric field distribution using...

The effects of impurities on mobilities measured in n-hexane using nano-second x ray ionization pulses are reported. A population redistribution occurred with the negative carrier species which was linearly dependent on impurity level. A connection between strong EHD effects and certain types of impurity is inferred.

It has recently been recognised that it is realistic to make predictions of the detailed sea surface shape typically up to 30 seconds ahead. This offers the prospect of substantially increasing the operating envelope in a wide range of marine operations. This article examines, from the point of view of a potential user of this technology, how the v...

Spark ignition engines operating on natural gas (NG) show advantages over petrol and diesel alternatives in terms of precatalyst emissions. However, such engines are affected much more than their petrol counterparts by the long combustion delay of the main fuel component, methane. The sensitivity of combustion delay to fuel/diluent chemistry means...

Natural gas is a promising alternative fuel to petrol for vehicles. However, one of the factors hampering the design of natural gas burning engines for domestic cars is the long delay from the time of ignition to the commencement of significant heat release. This is mainly due to the substantially endothermic phase during the early development of t...

 A recent generalisation of cross-correlation (GC-C) makes it possible to model transformations between data such as pairs of images by sets of parameterised functions as opposed to constant shifts, rotations etc. as employed in conventional cross-correlation. Typical applications of GC-C are in areas such as particle image velocimetry (PIV), or tw...

The possibility of deterministic prediction of the sea surface shape over time intervals that are useful in terms of ship applications has focused attention on the spatial as well as temporal aspects sea wave modelling. Simulation work shows that differences in the precision can arise when using spatial as opposed to temporal wave prediction scheme...

The previously introduced generalised cross-correlation, (GCC), function makes it possible to model spatial or temporal displacements which are smooth functions of position in contrast to conventional cross-correlation where such displacements are constants. This very much broadens the scope of correlation as a tool in areas such as flow or strain...

This paper is concerned with the implementation of a new image processing technique called Generalised Cross-Correlation designed to detect a two-dimensional displacement field between consecutive pictures of some object. The particular problem considered here is the determination of a flow field from experimental tank data. The method consists of...

The traditional view of the sea is as a stochastic process which can only be discussed in statistical terms. This article demonstrates that it is possible to take a deterministic view of sea-wave propagation which allows short term predictions to be made of the actual sea surface profile as a function of time. This has obvious applications in comme...

A physical model for simulating combustion systems in laminar flow reactors has been developed. The model is one-dimensional and includes transport phenomena. It is derived from conservation equations and thermodynamic relations. The present model is an extension of zero-dimensional models which were proposed by others. It enables one to accurately...

The paper describes a numerical model for the early stages of combustion in Natural Gas engines using linked CFD and detailed chemical kinetics. The importance of such a combustion device stems from the characteristics of natural gas which make it an attractive near-term olution for the automotive emissions problem. The 3-D simulation, which incorp...

The article considers a new approach to processing sonar signals used to determine the sea-bed profile. This is based upon a recent development termed generalisation cross-correlation which allows the correlation parameters to vary over the domain of interest and in turn this makes it viable to exploit to the full the coherence properties of the so...

Traditional cross-correlation considers situations where two functions or data sets are linked by a constant shift either in time or space. Correlation provides estimates of such shifts even in the presence of considerable noise corruption. This makes the technique valuable in applications like sonar, displacement or velocity determination and patt...

Part I of this article, ibid. 64, No. 2, 321-326 (1997; Zbl 0890.62045), introduced a generalization of cross-correlation in which the constant shift used in traditional cross-correlation is replaced by a function of time or space. This allows correlation to be applied globally to the whole domain of interest avoiding the need to compromise spatial...

The article demonstrates the recently introduced generalised frequency response technique developed for treating linear systems with time varying coefficients. The method is applied to determining the response of capacitor resistor systems with time varying dielectric loss where the loss spectrum has a 1/f character

Methods are introduced which describe the dielectric spectra of time varying dielectric coefficients whose bandwidth coincides that of the probing signals. It is shown that even if such effects are strictly linear in the time domain their spectral behaviour can readily make them be mistaken for non-linear process

The paper introduces the application of the generalised frequency response, to the determination of the frequency response of circuits with time varying elements. The approach is mainly via the analysis of illustrative cases based on active filters of increasing complexity. Where possible alternative, more conventional, analysis has also been perfo...

Simulations of methane combustion are developed for a synthetic atmosphere system where nitrogen is replaced as diluent with carbon dioxide. Special attention is given to the role of the detailed chemistry, using a scheme containing ∼100 separate reactions. The sensitivity of the results to the major reactions is analysed, and the approach to equil...

This paper examines non-uniformly sampled functions on a finite interval. the aim is to investigate what conditions must be satisfied in order to recover the baseband spectrum from such data. It is shown that the concept of band limitation inherent in Nyquist's theorem must be generalized into a quantity termed primary interval bandwidth limitation...

This study reports some preliminary steps in the development of techniques for simplifying the problem of analysing spatially propagating reactions in anisotropic multi-phase systems. The target situation is combustion in a spark ignition petrol engine; nevertheless the method described has a much broader range of application.Both present and futur...

Experimental measures are developed for the description of anisotropic growth in the early stages, of the flame kernel development in an operating spark ignition internal combustion engine. These measures are developments of the support area concept introduced by Bradley and Abdel-Gayed. By applying the technique of multi-scale analysis derived fro...

A texture analysis technique is presented, based on multiresolution Fourier analysis of images. Conventional subimage Fourier analysis produces results which are not easily assimilated. This paper proposes the use of colour to give an accessible display of such results. The described colour coding can, in principle, be applied in conjunction with a...

It has previously been recognised that it is possible to predict the shape of the sea surface (sea waves) in a deterministic fashion over periods of 20 to 30 seconds ahead in time. The resulting future sea wave information allows predictive control strategies for ship operation to be developed in various applications. For use with freely operating...

The results of a simple simulation model incorporating the cyclic fluctuations in flame velocity resulting from the corresponding variability in turbulence onset and generation imply that at low load conditions such fluctuations can induce changes of the order of many per cent in the indicated mean effective pressure (i.m.e.p.). The methods employe...

An extension of the concept of frequency response is introduced which can be applied to systems described by differential equations whose coefficients vary periodically or almost periodically with time. Such systems are not accessible to traditional frequency response function methods because while the governing equations may be linear in the time...

Although large structures, such as buildings, tall masts and bridges, often move by quite large amounts, their rates of movement are normally very low, so that they only generate low levels of acceleration. This makes the measurement of their responses (to loadings from wind, vehicular traffic, etc.) difficult when using currently employed methods,...

The article discusses nonuniform sampling specifically for the case of finite-length sets of data. The approach exploits the features of a finite interval and this restriction makes it possible to obtain the results presented using very simple analytical techniques. Much more complex methods have been used previously when the problem was treated ov...

This paper presents the use of multi-resolution Fourier analysis for the purpose of automatically identifying different tissue types and pathologies in magnetic-resonance images in medicine. The identification is based on the structure, or texture, of tissues as it appears in the image. While fractal-dimension analysis only exploits information equ...

This article examines the anisotropies in the long wavelength infrared spectra observed in strongly polar end-substituted straight chain alkanes. Comparison with the unsubstituted parent molecules suggest that dipole-dipole coupling is responsible for the anisotropies. A simple weak coupling analysis of the problem shows that the frequencies at whi...