A5070756174- Cryospheric studies and observations
- Landslides and related hazards
- Chaos control and synchronization
- Advanced MIMO Systems Optimization
- Advanced Wireless Communication Techniques
- Climate change and permafrost
- Radar Systems and Signal Processing
- Wireless Communication Networks Research
- Chaos-based Image/Signal Encryption
- Cognitive Radio Networks and Spectrum Sensing
- Fractal and DNA sequence analysis
- Winter Sports Injuries and Performance
- Wireless Body Area Networks
- Antenna Design and Analysis
- Power Line Communications and Noise
- Geology and Paleoclimatology Research
- Cooperative Communication and Network Coding
- Distributed Sensor Networks and Detection Algorithms
- Coastal and Marine Dynamics
- Millimeter-Wave Propagation and Modeling
- Geological formations and processes
- Radio Astronomy Observations and Technology
- Direction-of-Arrival Estimation Techniques
- Neural Networks and Applications
- PAPR reduction in OFDM
British Geological Survey
2017-2022
University of Bristol
2006-2022
Royal Holloway University of London
2020
At Bristol
2017
University of Leeds
2011-2016
Halliburton (United Kingdom)
2016
University of Oxford
2011
Fujitsu (United Kingdom)
2008-2009
Fujitsu (United States)
2008
Qinetiq (United Kingdom)
2001-2005
Abstract Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics, and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic water (AW) that rapidly melts undercuts marine‐terminating glaciers. Here we present new compilation Greenland assimilates seafloor thickness data through mass conservation approach. A 150 m horizontal resolution topography/bathymetric map constructed with seamless transitions at...
Rapid environmental change is driving the need for complex and comprehensive scientific information that supports policies aimed at managing natural resources through international treaties, platforms, networks.One successful approach delivering such has been development of Essential Variables climate (1), oceans (2), biodiversity (3), sustainable goals (4) (ECVs, EOVs, EBVs, ESDGVs, respectively).These efforts have improved consensus on terminology, identified essential sets measurements...
The feasibility of coexistence between radar and a communication system is investigated under log-normal shadowing conditions. A key element that enables sensing receiver to detect the presence prevent transmissions when interference may occur. Initial studies where each terminal does its own decision-making shows while bandsharing possible, stringent requirements, efficiency can be limited. Analytical simulation results illustrate cooperative leads an improved detection range, higher...
Abstract. There is widespread, but often indirect, evidence that a significant fraction of the bed beneath Greenland Ice Sheet thawed (at or above pressure melting point for ice). This includes beds major outlet glaciers and their tributaries large area around NorthGRIP borehole in ice-sheet interior. The ice-sheet-scale distribution basal water is, however, poorly constrained by existing observations. In principle, airborne radio-echo sounding (RES) enables detection from bed-echo...
Small mountain glaciers have short mass balance response times to climate change and are consequently very important for short‐term contributions sea level. However, a distinct research knowledge gap exists between (1) wider regional studies that produce overview patterns trends in glacier changes, (2) situ local scale emphasise spatial heterogeneity complexity responses climate. This study of small central Austria presents spatiotemporally detailed analysis changes geometry glaciological...
Abstract. Radar inference of the bulk properties glacier beds, most notably identifying basal melting, is, in general, derived from reflection coefficient. On scale an ice sheet, unambiguous determination is primarily limited by uncertainty englacial attenuation radio wave, which Arrhenius function temperature. Existing bed-returned power algorithms for deriving assume that rate regionally constant, not feasible at ice-sheet-wide scale. Here we introduce a new semi-empirical framework...
Abstract. We describe a new algorithm that automatically delineates the cliff top and toe of cliffed coastline from digital elevation model (DEM). The builds upon existing methods but is specifically designed to resolve very irregular planform coastlines with many bays capes, such as parts Great Britain. sequentially smooths shoreline vectors, generates orthogonal transects profiles minimum spacing equal DEM resolution, extracts position toe. Outputs include non-smoothed raster smoothed...
The real issues of communicating over radio channels with continuous time chaotic signals are addressed. Synchronized and nonsynchronized methods assessed. modeling (including multipath Doppler) is reviewed, then the effect on investigated. bandwidth efficiency communication systems discussed, compared to conventional methods. practical symbol synchronization equalization discussed. It pointed out that discussing these as spread spectrum often unhelpful, because a noise free reference signal...
Abstract Recent topographical and ground-penetrating radar (GPR) surveys of Kårsaglaciären, which is a small (<1 km 2 ) thin (<56 m) mountain glacier in Arctic Sweden, show that there are areas temperate ice the lowermost part glacier. This curious because we would expect such to have fully cold ablation zone. Specifically, with our analyses present geometry thickness prevailing climate, unable explain presence within snout Kårsaglaciären using models thermal structure. leads us...
In relation to opportunistic access radar spectrum, the impact of on a communication system is investigated in this paper. This paper illustrates that by exploring spatial and temporal opportunities spectrum therefore improving tolerance level interference, substantial increase throughput possible. Results are presented regarding swept radars WiMAX system. The results show SIR (Received signal received ratio), antenna radiation patterns rotation period estimation feasibility access.
New York State is pioneering a new approach to regulating its electric utility companies that expected usher in the distributed energy system of tomorrow. Among goals REV (Reforming Energy Vision) proceeding launched 2015 are 40% reduction greenhouse gas emissions from 1990 levels and mandate for 50% state's electricity be generated renewable resources by 2030. In 2014, 25% York's generation was produced renewables, which 80% hydropower. addition these other objectives, Public Service...
An analysis of the propagation characteristics communication links in personal sphere is presented. The results two wideband measurement campaigns 5.2 GHz band involving on-body multiple-input multiple-output (MIMO) arrays are reported. In first measurement, transmission takes place between antennas and a uniform linear array, positioned at close range with line-of-sight (LOS) conditions. Despite LOS operation, MIMO shown to offer significant increase information theoretic capacity system...
Abstract. Bed topography is a critical boundary for the numerical modelling of ice sheets and ice–ocean interactions. A persistent issue with existing products bed Greenland Ice Sheet surrounding sea floor poor representation coastal bathymetry, especially in regions floating near grounding line. Sparse data coverage, resultant coarse resolution at boundary, poses issues our ability to model flow advance retreat from present position. In addition, as fjord bathymetry known exert strong...
A new pre-FFT synchronisation method for OFDM is proposed and assessed, which gives improved performance in multipath channels. The technique can be used a range of signal parameters, channel environments. relative increase complexity over existing correlation-based methods less than 10%.
A correlation receiver is presented for communication using the symbolic dynamics of a chaotic system. system offers potential power efficient transmitters but many proposals to date have either been susceptible noise and distortion in channel, or are spectrally inefficient. The proposed has spectrum efficiency equivalent conventional BPSK 2 dB performance improvement AWGN. This achieved by exploiting diversity transmitted signal, whereby each data symbol influences pulse shape preceding...
Chaotic signals add to the design repertoire for radar. This paper discusses properties of chaotic signals, their generation and use, including transmitter hardware efficiency, with reference results in communications research recent theoretical practical sonar, development throughout world Practical issues arising from unique systems are considered. Phase locking target identification benefits also suggested. Results sonar experiments trials support prediction simulation findings given. It...
This paper presents an evaluation of the MIMO performance three candidate antenna array designs, each embedded within a PDA footprint, using indoor wideband channel measurements at 5.2 GHz alongside simulations. A model which employs plane-wave approximation was used to combine radiation patterns devices obtained from far-field pattern and multipath component parameters ray-tracer. The 4-element arrays were constructed different type element, despite diverse element directivities,...
Abstract. The subglacial environment of the Greenland Ice Sheet (GrIS) is poorly constrained, both in its bulk properties, for example geology, presence sediment, and water, interfacial conditions, such as roughness bed rheology. There is, therefore, limited understanding how spatially heterogeneous properties relate to ice-sheet motion. Here, via analysis two decades worth radio-echo sounding data, we present a new systematic beneath GrIS. We use independent methods quantify roughness:...
The symbolic dynamics method of communication using chaotic systems has previously been shown to offer performance better than conventional binary phase shift keying (BPSK), while also providing similar spectrum efficiency. This is achieved by exploiting diversity in the waveform, through a mechanism partial response signalling. In order achieve this performance, correlation for detection proposed, but complexity was high and only additive white Gaussian noise (AWGN) channels considered. It...
Glacier mass balance and gradient are fundamentally affected by changes in glacier 3D geometry. Few studies have quantified changing mountain geometry, not least because of a dearth suitable spatiotemporally distributed topographical information. Additionally, there can be significant uncertainty georeferencing historical data subsequent calculations the difference between successive surveys. This study presents multiple reconstructions associated response Kårsaglaciären, which is 0.89 ±...
In this brief, we consider methods to improve the performance of chaotic communication schemes. We study a system using receiver which explicitly includes presence noise in channel. show how choice dynamical generating transmitted signal is crucial. observe large variation bit error rate as parameters maps are changed, and propose simple explanation for variation.
This article reviews wireless enabling technologies to support interworking of heterogeneous networks, and covers two relevant topics; personal area networks multistandard terminals. The variability the PAN channel is demonstrated, implications for air interface design are discussed. To ensure effective operation in shared spectrum, radio resource management medium access control strategies PANs also It recognized that terminal cost has significant user acceptance; therefore, by combining...
Recently, there has been an explosion of growth in research on MIMO systems, but little published characterising performance realistic environments. This paper quantifies the WLANs outdoor environments, and compares between spatial multiplexing space time block coding processing approaches. Packet Error Rate (PER) throughput results are presented under different channel conditions. A WLAN physical layer simulator employing techniques a propagation modelling tool combined order to evaluate...
This paper addresses pre-FFT synchronisation for orthogonal frequency division multiplex (OFDM) under varying multipath conditions. To ensure the most efficient data transmission possible, there should be no constraints on how much of cyclic prefix (CP) is occupied by intersymbol interference (ISI). Here a solution timing proposed, that is, robust even when strongest components are delayed relative to first arriving paths. In this situation, existing methods perform poorly, whereas proposed...
Orthogonal frequency-division multiplex (OFDM) offers a low-complexity solution to equalization in multipath channels but does so by increasing the symbol period. This places limit on mobility of such systems since time variations channel during period introduce intercarrier interference (ICI), hence, degrading performance. Solutions reduce ICI literature require high degree processing. Increasing terminal also greater requirements synchronization processing track rapidly changing channel....