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H-NS family proteins, bacterial xenogeneic silencers, play central roles in genome organization and in the regulation of foreign genes. It is thought that gene repression is directly dependent on the DNA binding modes of H-NS family proteins. These proteins form lateral protofilaments along DNA. Under specific environmental conditions they switch to bridging two DNA duplexes. This switching is a direct effect of environmental conditions on electrostatic interactions between the oppositely charged DNA binding and N-terminal domains of H-NS proteins. The Pseudomonas lytic phage LUZ24 encodes the protein gp4, which modulates the DNA binding and function of the H-NS family protein MvaT of Pseudomonas aeruginosa. However, the mechanism by which gp4 affects MvaT activity remains elusive. In this study, we show that gp4 specifically interferes with the formation and stability of the bridged MvaT–DNA complex. Structural investigations suggest that gp4 acts as an ‘electrostatic zipper’ between the oppositely charged domains of MvaT protomers, and stabilizes a structure resembling their ‘half-open’ conformation, resulting in relief of gene silencing and adverse effects on P. aeruginosa growth. The ability to control H-NS conformation and thereby its impact on global gene regulation and growth might open new avenues to fight Pseudomonas multidrug resistance.

Bacterial xenogeneic silencers, the H-NS family proteins play central roles in genome organization and in the regulation of foreign genes acquired from phages or through horizontal gene transfer. It is thought that the repression of these genes is directly dependent on their DNA binding modes. H-NS family proteins bind along DNA, forming lateral protein filaments, in which the H-NS protomers adopt a "half-open" conformational state. Under specific environmental conditions and without dissociating from DNA, these proteins adopt an "open" conformational state which can bridge two DNA duplexes. This switching is a direct effect of environmental conditions on electrostatic interactions between the oppositely charged DNA binding and N-terminal domains of H-NS proteins. The Pseudomonas lytic phage LUZ24 encodes the gp4 protein, which binds the H-NS family protein MvaT of Pseudomonas aeruginosa. Binding of gp4 was suggested to inhibit the silencing of phage LUZ24 DNA by MvaT. However, the mechanism by which gp4 modulates MvaT activity remains elusive. In this study, we show that gp4 specifically interferes with the formation and stability of the bridged MvaT-DNA complex. Structural investigations by NMR spectroscopy revealed that gp4 acts as an "electrostatic zipper" between the N-terminal and DNA binding domains of MvaT protomers and stabilizes a structure resembling their "half-open" conformation. Based on these observations, we propose that binding of gp4 promotes a half-open bridging-incompetent state of MvaT, resulting in relief of MvaT-mediated gene silencing and adverse effects on P. aeruginosa homeostasis and growth. Conformational switching of H-NS proteins driven by phage "early proteins" provides a novel anti-repression mechanism. The ability to control H-NS conformation and thereby its impact on global gene regulation and growth might open new avenues to fight Pseudomonas multidrug resistance.

Conventional track circuit condition monitoring systems are fixed at the wayside, with each installation reporting on a single track circuit. In this work, we present a custom-built, sensitive, magnetic field detection system, which can be fitted to the underside of a rail vehicle. With this system installed, some characteristics of an operating track circuit can be monitored from the vehicle whilst it is in motion. By using appropriate analysis techniques, it is possible to identify the signatures of equipment relating to audio frequency track circuits, the topic of this work. Analysing the signatures of track circuit equipment demonstrated that there were clear differences between track circuit assets. By building on other research into the behaviours of failing track circuits, and continuing to conduct this research, the authors believe that it is possible, and beneficial, to perform condition monitoring of track circuits from low-cost equipment mounted on the train. Coupling this with advanced analysis techniques will allow predictive maintenance of track circuits with very little capital outlay.

A half-space electromagnetic model of human skin over the band 30-300 GHz was constructed and used to model radiometric emissivity. The model showed that the radiometric emissivity rose from 0.4 to 0.8 over this band, with emission being localized to a layer approximately one millimeter deep in the skin. Simulations of skin with differing water contents associated with psoriasis, eczema, malignancy, and thermal burn wounds indicated radiometry could be used as a non-contact technique to detect and monitor these conditions. The skin emissivity of a sample of 30 healthy volunteers, measured using a 95 GHz radiometer, was found to range from 0.2 to 0.7, and the experimental measurement uncertainty was ±0.002. Men on average were found to have an emissivity 0.046 higher than those of women, a measurement consistent with men having thicker skin than women. The regions of outer wrist and dorsal forearm, where skin is thicker, had emissivities 0.06-0.08 higher than the inner wrist and volar forearms where skin is generally thinner. Recommendations are made to develop a more sophisticated model of the skin and to collect larger data sets to obtain a deeper understanding of the signatures of human skin in the millimeter wave band. Bioelectromagnetics. 2017;9999:XX-XX. © 2017 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.

This work presents an objective performance analysis of statistical tests for edge detection which are suitable for textured or cluttered images. The tests are subdivided into two-sample parametric and non-parametric tests and are applied using a dual-region based edge detector which analyses local image texture difference. Through a series of experimental tests objective results are presented across a comprehensive dataset of images using a Pixel Correspondence Metric (PCM). The results show that statistical tests can in many cases, outperform the Canny edge detection method giving robust edge detection, accurate edge localisation and improved edge connectivity throughout. A visual comparison of the tests is also presented using representative images taken from typical textured histological data sets. The results conclude that the non-parametric Chi Square and Kolmogorov Smirnov statistical tests are the most robust edge detection tests where image statistical properties cannot be assumed a priori or where intensity changes in the image are nonuniform and that the parametric Difference of Boxes test and the Student’s t-test are the most suitable for intensity based edges. Conclusions and recommendations are finally presented contrasting the tests and giving guidelines for their practical use while finally confirming which situations improved edge detection can be expected.

Occupant presence and behaviour have a large impact on building energy performance. With the availability of low cost and affordable sensors, accurate occupancy detection by combining sensor stream data with machine learning approaches becomes possible. In this paper, we propose a novel dynamical hidden semi-Markov model (D-HSMM) which can accurately detect occupancy pattern from sensor data stream in real time. Our approach extends traditional hidden Markov (HMM) and hidden semi-Markov models (HSMM). The novelty of the proposed approach consists in 1) a new dynamic duration modelling way in which the duration is dynamically changing, instead of using fixed duration in traditional HSMM based models; 2) a new approach to state prediction (i.e. occupant presence or absence in this case) based on a weighted function with partially available observations instead of using the whole set of observations. In order to evaluate the performance of our model, we have compared our results with traditional HMM and HSMM approaches. The experimental evaluation shows that our D-HSMM model outperforms the conventional HMM and HSMM-based approaches with very high accuracy.

We present a millimeter radar for threat level evaluation developed for the detection concealed threats, such as guns and person borne improvised explosive devices (PBIED). The system uses a Gaussian optic lens antenna to achieve stand-off ranges up to 25 m. Ultra-wideband swept frequency radar, using direct detection receivers, is implemented to achieve short radar range resolution . The system is capable of detecting a wide range of objects positioned in front of the body by interpretation of the scattered waveform. Threat detection is rendered autonomously by a neural network that processes the scattered polarimetric, depth domain radar waveforms. The system may be configured to alarm or reject certain classes of objects, allowing for the detection of specific or broad spectrum threats. The radar system is portable and manually steered by the operator to enable standoff monitoring of walking human targets in real time. A video feed provides the operator with a wide field of view that allows tracking of persons and greatly facilitates aiming of the sensor. Rapid (1 ms) radar sweep times and fast signal acquisition and processing are implemented to provide threat detection at video frame rates (30 fps). Performance parameters for the detection of hand-guns and simulated PBIED are presented for ranges up to 25 m.

This paper describes how information about the electro- magnetic structure of targets can be obtained from direct detection radar techniques, where the relative phase of the transmitted and re- ceived signals is not measured. A comparison is made between the re- solved structure of a simple test target from an ultra wide band, pulse synthesis direct detection radar system at 14{40GHz and an equiv- alent heterodyne radar receiver where phase information is recorded. The test targets employed are wax sheet of thickness 20mm and 80mm which are illuminated alone and in contact with the human body. A vector network analyser is used as the radar system. The simplicity of constructing ultra wide band direct detection radar systems combined with their cost makes the use of such radar systems appealing for appli- cations such as concealed threat detection and non-destructive testing, where absolute range to the target, if required, can be determined by other methods.

The authors present transmission data, taken at Ka (36GHz) and W (95 GHz) bands in\ud the millimetre-wave region of the electromagnetic spectrum, for various dressing materials used in the\ud treatment and management of burn wounds. The results show that such materials are highly transparent\ud (typically > 90% transmission) and, in their dry state, will permit the sensing of the surface of the skin\ud through the thick layers (> 2 cm) of different dressings typically applied in medical treatment of burn\ud wounds. Furthermore, the authors present emissivity data, taken at the same frequency bands, for\ud different regions of human skin on the arm and for samples of chicken flesh with and without skin\ud and before and after localised heat treatment. In vivo human skin has a lower emissivity than chicken\ud flesh samples, 0.3–0.5 compared to 0.6–0.7. However, changes in surface emissivity of chicken samples\ud caused by the short-term application of heat are observable through dressing materials, indicating the\ud feasibility of a millimetre-wave imaging to map changes in tissue emissivity for monitoring the state of\ud burn wounds (and possibly other wounds) non-invasively and without necessitating the removal of the\ud wound dressings.

There is now, more than ever before, a need for technologies that enable the screening of people from a distance. A wide variety of weapons can be easily concealed under clothing and carried into crowded public sites to target national infrastructure, spread fear, and inflict mass murder and casualties. The most feared and devastating terrorist weapon is the suicide bomb or person borne improvised explosive device (PBIED). Such devices are relatively simple to conceal on the body, and successful detection is required at considerable distance or stand-off range before the bomber reaches the target area.

The detection and identiflcation of metal items and, in particular weapons, of linear size ‚ 10cm, concealed upon the human body, is demonstrated as being entirely feasible by using a phased array of suitably ultra wide band transceivers. The complex natural resonances and especially the fundamental resonance, are excited by ultra wide band, stepped frequency continuous wave illumination of the target, using a phased array of antennae to focus the radiation. Broadband illumination of the target with microwave radiation of suitable frequency range (Typically 0.3{3GHz for handgun sized objects) excites low order complex natural resonances and the late time response of the concealed item can be spatially located using phased array imaging techniques. Further processing of the late time response enables classiflcation of the concealed object, based on the complex natural resonant frequencies of the object, so that threat items such as handguns and knives can be difierentiated from benign items such as mobile phone handsets and cameras.

The detection and identiflcation of conducting objects using electromagnetic pulses to excite circulating eddy currents within the object is demonstrated by numerical simulation using a flnite element time domain electromagnetic solver. The ability to discriminate between objects is based on the decay rate of the induced currents in the object, typically » 100"S. The decay rates are difierent for a wide variety of everyday objects, allowing threat objects such as handguns, grenades and knives to be discriminated from benign objects such as mobile phones handsets, watches, keys, etc.. Crucially, the time constant characterising an object depends only upon the electrical properties of the object (conductivity) and the shape and size of the object; the orientation of the object is irrelevant. This aspect independence of temporal current decay rate forms the basis of a potential object detection and identiflcation system. By application of an algorithm based on the generalized pencil of function method, the authors demonstrate the ability to efiectively count and indentify multiple objects carried in close proximity providing that the objects do not have very similar time constants and that signal to noise ratio is high.

The authors discuss and demonstrate the feasibility of using ultra wide band microwave radar to detect and identify small arms flre. Detection and tracking is by standard radar techniques, but identiflcation is carried out by exciting the projectiles Complex Natural Resonances and using this aspect independent information to assign a caliber to the incoming projectiles. The typical sizes of small arms projectiles (calibers 5.56mm through to 13mm) imply that ultra wide band illumination in the microwave region of the spectrum between 1.5{5.5GHz is required to excite these object's fundamental resonances. The authors give a discussion of the efiects of motion on the quality of the complex natural resonance data obtainable and present both simulated and laboratory data for the radar cross section of three difierent caliber projectiles (5.56mm, 7.62mm and 13mm).

The Boundary Element Method for solving the Laplace and Poisson equations for electrostatic systems will be outlined, with the emphasis on 3D systems and the commercial CPO programs. Some applications to charged particle optics will be described. Since the BEM is a charge-based method it is ideally suited for systems that include space-charge and/or cathodes. It is also exceptionally accurate and can deal easily with electrodes of very different sizes. Several ‘benchmark tests will be presented, in which systems with known analytic solutions are used to illustrate the accuracy and versatility of the programs.

A free-wave, transmission only technique for the determination of complex permittivity in the millimetre (mm)-wave band 14-40 GHz of planar samples of textiles is presented. With this method an accurate alignment of source and detector horns is not required and time gating methods to reduce or remove standing wave interference between horns is replaced by a data smoothing process. The technique is novel as phase information from the transmitted wave is not required to determine the complex permittivity. The textiles investigated are denim (cotton) and cow leather (two colours, red and beige). This method is shown to be simple to set up, easy to use and fast when compared with other methods such as free-wave reflectance and transmittance or Fabry-Perot cavity and gives results which are accurate enough for most of the practical applications. A significant difference in the absorption of mm-wave power between the two leather samples is observed. This can be explained by the different chemical composition of the two leather samples, investigated using a scanning electron microscope with electron dispersive spectrometry and which is almost certainly a result of the colouring process employed.

The threat of concealed weapons, explosives and contraband in footwear, bags and suitcases has led to the development of new devices, which can be deployed for security screening. To address known deficiencies of metal detectors and x-rays, an UWB 3D microwave imaging scanning apparatus using FMCW stepped frequency working in the K and Q bands and with a planar scanning geometry based on an x y stage, has been developed to screen suspicious luggage and footwear. To obtain microwave images of the concealed weapons, the targets are placed above the platform and the single transceiver horn antenna attached to the x y stage is moved mechanically to perform a raster scan to create a 2D synthetic aperture array. The S11 reflection signal of the transmitted sweep frequency from the target is acquired by a VNA in synchronism with each position step. To enhance and filter from clutter and noise the raw data and to obtain the 2D and 3D microwave images of the concealed weapons or explosives, data processing techniques are applied to the acquired signals. These techniques include background subtraction, Inverse Fast Fourier Transform (IFFT), thresholding, filtering by gating and windowing and deconvolving with the transfer function of the system using a reference target. To focus the 3D reconstructed microwave image of the target in range and across the x y aperture without using focusing elements, 3D Synthetic Aperture Radar (SAR) techniques are applied to the post-processed data. The K and Q bands, between 15 to 40 GHz, show good transmission through clothing and dielectric materials found in luggage and footwear. A description of the system, algorithms and some results with replica guns and a comparison of microwave images obtained by IFFT, 2D and 3D SAR techniques are presented.

This paper presents part of a feasibility study into the use of the aperture synthesis passive imaging technique to screen vehicles for persons. The aperture synthesis technique is introduced and shown how in the near-field regime of a vehicle screening scenario that a three-dimensional imaging capability is possible. A suggested antenna receiver array is presented and the three-dimensional point spread function which this enables is calculated by simulation. This shows that over the majority of the inside of the vehicle the spatial resolution in all three spatial dimensions is of or less than the radiation wavelength, which at the suggested operational radiation frequency of 20 GHz is 1.5 cm. A radiation transport model that estimates the radiation temperatures of persons and backgrounds when viewing the vehicle either from the side or the top is presented, such a model being useful in the design of vehicle screening systems and as a basis for interpretation codes to assist operators in recognising persons in vehicles.

This paper investigates by simulation the use of the three-dimensional aperture synthesis imaging technique to image three-dimensional extended sources. Software was written to access the three-dimensional information from computer graphics models in the formats of *.dxf and *.3ds and use these to generate synthetic cross-correlations, as if they would have been generated by an aperture synthesis antenna/receiver array measuring the radiometric emission from the three-dimensional object. A three-dimensional (near-field) aperture synthesis imaging algorithm generates [1] a voxel image of the three-dimensional object. Images created from a sphere indicate faithful reproduction about a single phase centre when the radius of the sphere is less than the Fresnel scale. However, for larger spheres, definition in the threedimensional imagery suffers and a phenomenon, referred to in this paper as Fresnel noise, appears in the image. Images of objects larger than the Fresnel scale can be created by having multiple smaller images, each having a size approximately of the Fresnel scale and centred on separate phase centres. Using the software to generate threedimensional imagery of a person, to demonstrate capabilities for portal security screening, indicates the technique works to first order. Improvements are needed in the software to improve the spatial sampling of the radiometric fields from the three-dimensional objects and implement a volumetric image mosaicking technique to remove the Fresnel noise.

Recently it has been noted that user behaviour can have a large impact on the final energy consumption in buildings. Through the combination of mathematical modelling and data from wireless ambient sensors, we can model human behaviour patterns and use the information to regulate building management systems (BMS) in order to achieve the best trade-off between user comfort and energy efficiency. In this work, we have modelled user occupancy and activity patterns using Machine Learning approaches. We have applied non-linear multiclass Support Vector Machines (SVMs) to deal with the complex nature of the data collected from various sensors to accurately identify user occupancy and activities of daily living (ADL) patterns. To validate our results, we also used other methodologies (i.e. Hidden-Markov Model and k-Nearest Neighbours). The experimental results show that our proposed approach outperforms the other methods for the scenarios evaluated.

The incorporation of decision maker preferences is often neglected in the Evolutionary Multi-Objective Optimisation (EMO) literature. The majority of the research in the field and the development of EMO algorithms is primarily focussed on converging to a Pareto optimal approximation close to or along the true Pareto front of synthetic test problems. However, when EMO is applied to real-world optimisation problems there is often a decision maker who is only interested in a portion of the Pareto front (the Region of Interest) which is defined by their expressed preferences for the problem objectives. In this paper a novel preference articulation operator for EMO algorithms is introduced (named the Weighted Z-score Preference Articulation Operator) with the flexibility of being incorporated a priori, a posteriori or progressively, and as either a primary or auxiliary fitness operator. The Weighted Z-score Preference Articulation Operator is incorporated into an implementation of the Multi-Objective Evolutionary Algorithm Based on Decomposition (named WZ-MOEA/D) and benchmarked against MOEA/D-DRA on a number of bi-objective and five-objective test problems with test cases containing preference information. After promising results are obtained when comparing WZ-MOEA/D to MOEA/D-DRA in the presence of decision maker preferences, WZ-MOEA/D is successfully applied to a real-world optimisation problem to optimise a classifier for concealed weapon detection, producing better results than previously published classifier implementations.

Data fragmentation is one of the primary techniques that has been used in partitioning and developing distributed database systems (DDBs). Database partitioning technique improves the performance of the system throughput and reduces the amount of irrelevant data to be accessed and transferred among different sites in DDBs. We propose a technique that splits the database relations into pair-wise disjoint fragments, which would be allocated to the DDBs sites during the process of allocation. This technique reduces the data transferred between the sites during the applications execution, minimizes the communication cost needed for processing applications, handles the database queries and meets their future needs, guarantees the ability of processing a given portion of a given transaction in all sites, and improves the applications speed and efficiency by minimizing the number of fragments to be accessed. We have also developed a fragmentation tool that is interactive, full functional and easy to use...

A technique is described of simulating thermionic cathodes in the Boundary Element Method by replacing the space charges in the cathode region by a set of thin sheets of charge. These sheets are subdivided into segments in the same way that the cathode itself is subdivided. This technique has been applied to cathodes that have zero and non-zero temperature T. It is shown that for T>0 the potential and position of the virtual cathode is well reproduced. Planar and non-planar cathodes are considered as well as unsaturated cathodes.

The effects of electron–electron coulomb interactions have been simulated by a general computational technique that can be applied to almost any system, independently of the shape of the beam or the regimes that might be present, provided that the ‘closest-encounter’ approximation is valid for the system. The technique has been applied to the ‘benchmark test’ of the energy spreading in a converging round beam. The results are compared with previous analytical results.

Analysis of the reflection spectra of chiral smectic liquid crystal phases is used to provide detailed information on physical parameters, including refractive indices, helicoidal pitch and tilt angle. Numerical models of the antiferroelectric and ferroelectric phases are constructed, based on a 4 × 4 matrix technique, and a downhill simplex algorithm is employed to fit the model to reflection spectra measured from free-standing films of the materials of interest. The temperature dependence of the refractive indices, dispersion, tilt angle and pitch are reported for three different liquid crystalline materials. The accuracy of the fitting method is around 1%, better than the experimental error, and this is confirmed by comparison of the parameters determined by the fitting program with those measured by independent methods.

We have constructed a simple and inexpensive diode laser spectrometer in which the source is locked to and tracked by a scanning Fabry–Perot interferometer and in which absolute frequency measurements are made by markers generated by a further Fabry–Perot interferometer, itself locked either to a selected spectral line of the sample or to the saturated absorption of a D2 line in atomic Rb at 780 nm. With this technique we have been able to obtain near-continuous spectra stretching over the range from 12 640 to 12 780 cm-1 at Doppler-limited resolution. In this paper we describe the principles of the spectrometer along with absolute frequency measurements of a number of overtone rovibrational transitions in two isotopomers of acetylene. The combination relations formed by these transitions demonstrate the accuracy of our measurements to be typically ±0.0002 cm-1.

Angle and spin–orbit resolved photoelectron spectra of O 2 are presented in the photon energy range 13.06–13.15 eV where strong autoionization processes dominate the spectra. The angular measurements have been obtained using a newly constructed photoelectron spectrometer featuring a magnetic angle-changing device. β -Parameters and intensity ratios have been obtained for the two spin–orbit components of the O 2 + X 2 Π g ground ionic state.

The three dimensional (3D) aperture synthesis imaging technique investigated here is a generalisation of the classic twodimensional radio astronomy technique with refinements for the near-field so it can be applied a personnel security screening portal. This technique can be viewed as a novel form of diffraction emission tomography and extends previous 3D aperture synthesis imaging research using matrix inversion techniques [1]. Simulations using three-dimensional Fourier transforms to create three-dimensional images from simulated three-dimensional visibility functions illustrate the Abbe microscopy resolution should be achievable in three dimensions simultaneously in a single sensor. The field-of-view is demonstrated to be limited by Fresnel scale effects and a means to over coming this by processing sub-sets of local visibility functions with different phase centres throughout the imaging volume is presented. The applications of this technique to a full 3D imaging security screening portal is explored and a route to extending simulation software for market driven imaging scenarios is discussed.

This paper examines the suitability and potential of reducing the acquisition requirements of a novel radiation mapper through the application of the non-linear deconvolution technique, CLEAN. The radiation mapper generates a threshold image of the target scene, at a user defined distance, using a single pixel detector manually scanned across the scene . This paper provides a discussion of the factors involved and merits of incorporating CLEAN into the system. In this paper we describe the modifications to the system for the generation of an intensity map and the relationship between resolution and acquisition time for a target scene. The factors influencing image fidelity for a scene are identified and discussed with the impact on fill-factor of the intensity image, which in turn determines the ability of the operator to accurately identify features of the radiation source within a target scene. The CLEAN algorithm and its variants have been extensively developed by the radio astronomy community to improve the image fidelity of data collected by sparse interferometric arrays. However, the algorithm has demonstrated surprising adaptability including terrestrial imagery, as detailed in Taylor et al. SPIE 9078-19 and Bose et al., IEEE 2002. CLEAN can be applied directly to raw data via a bespoke algorithm. However, this investigation is a proof-of-concept and thus requires a well tested verification method. We have opted to use the public ally available implementation of CLEAN found in the Common Astronomy Software Applications (CASA) package. The use of CASA for this purpose dictates the use of simulated input data and radio astronomy standard parameters. Finally, this paper presents the results of applying CLEAN to our simulated target scene, with a discussion of the potential merits a bespoke implementation would yield.

This paper investigates the application of the CLEAN non–linear deconvolution method to Late Time Response (LTR) analysis for detecting multiple objects in Concealed Threat Detection (CTD). When an Ultra-Wide Band (UWB) frequency radar signal is used to illuminate a conductive target, surface currents are induced upon the object which in turn give rise to LTR signals. These signals are re-radiated from the target and the results from a number of targets are presented. The experiment was performed using double ridged horn antenna in a pseudo-monostatic arrangement. A Vector network analyser (VNA) has been used to provide the UWB Frequency Modulated Continuous Wave (FMCW) radar signal. The distance between the transmitting antenna and the target objects has been kept at 1 metre for all the experiments performed and the power level at the VNA was set to 0dBm. The targets in the experimental setup are suspended in air in a laboratory environment. Matlab has been used in post processing to perform linear and non-linear deconvolution of the signal. The Wiener filter, Fast Fourier Transform (FFT) and Continuous Wavelet Transform (CWT) are used to process the return signals and extract the LTR features from the noise clutter. A Generalized Pencil-of-Function (GPOF) method was then used to extract the complex poles of the signal. Artificial Neural Networks (ANN) and Linear Discriminant Analysis (LDA) have been used to classify the data.

The risk of attacks on travelling public has led to changes in security screening at airports. After the shoe bomber in 2001, each passenger must remove shoes, which might contain concealed threats to be x-rayed individually, which is inconvenient to passengers as well as airlines. An alternative approach is an Ultra Wide Band (UWB) Microwave Footwear Scanner swept between 15 to 40 GHz, which detects threats concealed within the shoes, while they are still worn. A prototype system is tested, which demonstrates the ability to detect concealed metal and dielectric objects. Results are compared with Finite Element Modelling simulations.

This paper investigates the use of Late Time Response (LTR) analysis for detecting multiple simulated objects using via Finite Element Analysis (FEA) in concealed object detection. The LTR results from a pair of simulated targets are presented individually and present within the same simulation. The simulation used a plane wave to represent the Ultra Wide-Band (UWB) signal from a Vector Network Analyser (VNA). The simulated targets are suspended in air and the perimeter of the environment is a perfectly matched layer. To allow for the de-convolution of the signal and the removal of background clutter post processing has been applied.

In this paper, a parameter extraction technique of a single- and a two-diode photovoltaic (PV) solar cell models using MATLAB/Simulink are presented. To reduce the computational time, the proposed method uses an accurate iterational technique and limits the inputs to four parameters, which are normally provided by the manufacturers' datasheets. Derived models are validated by plotting their I-V characteristics and compared to a photovoltaic (PV) cell under variable conditions of solar irradiance and temperature. The main contribution of this work is to validate the utilization of the two-diode model as a better representative model of a PV cell. This is important particularly at low levels of solar irradiance and temperature.

The naked eye is capable of perceiving electromagnetic radiation in a narrow band of frequencies, known as the optical spectrum. Working with low energy radiation outside the optical spectrum presents distinct difficulties, requiring the use of apparatus to measure invisible and intangible electromagnetic radiation. The apparatus, incorporating a Wiimote, and associated method are presented for a small, easily maintained and operated, low cost system for the characterisation of practical RF radiation sources in the microwave and millimetre-wave frequency bands.

Symmetric (e,2e) differential cross section measurements for argon at an incident energy of 64.6 eV are presented from the coplanar to the perpendicular plane geometry. The outgoing electrons were detected at symmetric scattering angles and with the same energy. These measurements are compared with analogous results at the same incident energy using helium as the target. The argon (e,2e) cross section shows a rich and complex structure as the scattering geometry changes, while the very deep interference minimum found in helium is missing.

The charge‐tube method is an accurate way of assigning the space‐charge of a beam in computational simulations of charged particle systems. The method is described and is compared with the traditional charge‐cell method.

Two investigations have been carried out of the helium (e,2e) process. The first concerns the sharp dip that exists at an incident electron energy of 64.6eV and for equal energies and angles of the two outgoing electrons. The sensitivity of this dip to the asymmetry of the angles of the outgoing electrons has been measured and it has been found that the dip exists over a wide range of asymmetric angles, but with an almost constant angle between the two electrons. In the second investigation a new 'magnetic angle-changing' technique has been used to observe the two outgoing electrons when one of them moves in the same direction as the incident electron and the other moves in the opposite direction, and a peak has been found in the triple differential cross section when the incident electron energy is 40eV and outgoing energies are 4 and 11eV.