Fundamental issues in antenna design for microwave medical imaging applications

This paper surveys the development of microwave medical imaging and the fundamental challenges associated with microwave antennas design for medical imaging applications. Different microwave antennas used in medical imaging applications such as monopoles, bow-tie, vivaldi and pyramidal horn antennas are discussed. The challenges faced when the latter used in medical imaging environment are detailed. The paper provides the possible solutions for the challenges at hand and also provides insight into the modelling work which will help the microwave engineering community to understand the behaviour of the microwave antennas in coupling media

Breast cancer detection using microwave holography

Breast cancer is one of the most common forms of cancer in women. X-ray mammography is the most widely used technique for early detection but has limitations. In this paper, an alternative approach for breast cancer detection using microwave imaging is presented. This is based upon microwave indirect holographic approach, central to which is the use of a synthetic reference beam. This approach has benefits in terms of simplicity and expense. Experimental results using a simple breast phantom are included to demonstrate the potential of this approach

An investigation of reduced size planer fed microstrip patch antennas

The primary goal of this research work is to investigate the use of slot loading in reduced size planar fed microstrip patch antennas and develop new antenna structures based on this technique. At present, little theoretical investigation or design methodology exists to support the design of compact structures and research in this field is largely empirical. Moreover, little work exists on the use of planar fed designs. This necessitates a primary requirement to firstly address this knowledge gap. To facilitate this, a mathematical modelling technique that can be applied to such structures is developed. This is based upon the segmentation and Green's function approach. Using this model, the performance of slot loaded structures in terms of circuit characteristics including resonant frequency, input impedance, and Q factor is determined. Using this knowledge, a design procedure is established and subsequently used to provide a framework for the design of novel slot loaded antennas for specific applications. Several new slot loaded patch antenna configurations are designed that produce size reduction whilst allowing the use of a planar feed. The validity of the designs are confirmed through the use of commercial full-wave modelling software package Ensemble. Three linear polarised antennas are presented which are shown to achieve size reduction of 12, 40 and 55% respectively. Several compact circular polarised antenna structures are successfully implemented producing size reduction of up to 43%. A novel design for a reduced size antenna with a dual frequency response is also presented with a tuneable frequency ratio of between 1.03 — 2.0. Prototypes of the aforementioned antennas are fabricated and tested, and practical results are shown

An investigation of reduced size planar fed microstrip patch antennas

The primary goal of this research work is to investigate the use of slot loading in reduced size planar fed microstrip patch antennas and develop new antenna structures based on this technique. At present, little theoretical investigation or design methodology exists to support the design of compact structures and research in this field is largely empirical. Moreover, little work exists on the use of planar fed designs. This necessitates a primary requirement to firstly address this knowledge gap. To facilitate this, a mathematical modelling technique that can be applied to such structures is developed. This is based upon the segmentation and Green's function approach. Using this model, the performance of slot loaded structures in terms of circuit characteristics including resonant frequency, input impedance, and Q factor is determined. Using this knowledge, a design procedure is established and subsequently used to provide a framework for the design of novel slot loaded antennas for specific applications. Several new slot loaded patch antenna configurations are designed that produce size reduction whilst allowing the use of a planar feed. The validity of the designs are confirmed through the use of commercial full-wave modelling software package Ensemble. Three linear polarised antennas are presented which are shown to achieve size reduction of 12, 40 and 55% respectively. Several compact circular polarised antenna structures are successfully implemented producing size reduction of up to 43%. A novel design for a reduced size antenna with a dual frequency response is also presented with a tuneable frequency ratio of between 1.03 — 2.0. Prototypes of the aforementioned antennas are fabricated and tested, and practical results are shown.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Dynamic Carbon-Constrained EPEC Model for Strategic Generation Investment Incentives with the Aim of Reducing CO2 Emissions

According to the European Union Emissions Trading Scheme, energy system planners are encouraged to consider the effects of greenhouse gases such as CO 2 in their short-term and long-term planning. A decrease in the carbon emissions produced by the power plant will result in a tax decrease. In view of this, the Dynamic carbon-constrained Equilibrium programming equilibrium constraints (DCC-EPEC) Framework is suggested to explore the effects of distinct market models on generation development planning (GEP) on electricity markets over a multi-period horizon. The investment incentives included in our model are the firm contract and capacity payment. The investment issue, which is regarded as a set of dominant producers in the oligopolistic market, is developed as an EPEC optimization problem to reduce carbon emissions. In the suggested DCC-EPEC model, the sum of the carbon emission tax and true social welfare are assumed as the objective function. Investment decisions and the strategic behavior of producers are included at the first level so as to maximize the overall profit of the investor over the scheduling period. The second-level issue is market-clearing, which is resolved by an independent system operator (ISO) to maximize social welfare. A real power network, as a case study, is provided to assess the suggested carbon-constrained EPEC framework. Simulations indicate that firm contracts and capacity payments can initiate the capacity expansion of different technologies to improve the long-term stability of the electricity market

A Contactless Characterization of CNT/Epoxy Nanocomposites behavior under acid exposure

The use of polymer nanocomposites is ubiquitous in every industry. The high corrosion resistance and chemical durability of CNT/Epoxy nanocomposites make them suitable for chemical plants, oil industries, and hydrogen storage. However, unexpected failures have been reported for chemicals that unavoidably penetrate, provoking deterioration and degradation of the composite constituents. Conventional methods are impractical for evaluating structural health conditions because they often require disassembly of the structure and complex post-processing analysis. Contactless material characterization methods, on the other hand, are rather promising tools. Nevertheless, the influence of nanofillers and acid attack diffusion on wireless signals has yet to be explored. In this study, the effects of acid attack periods (i.e. one, week, two weeks, and month) on the scattering parameters of microstrip antennas ere investigated using a vector network analys. Additionally, an idealised multi-scale modelling approach was developed to study the influence of electrical conductivity and porosity volume changes on return loss (S11). The data showed that the diffusion of ions altered the specimen properties as time progressed. The increment in the electrical conductivity and porosity volume is reflected especially during the month-long period. Finally, in this study, it was found that wireless methods can be implemented to characterise materials which are beneficial for real-time in-situ structural health monitoring

The functional diversity of fish assemblages in the vicinity of oil and gas pipelines compared to nearby natural reef and soft sediment habitats

We would like to thank skippers John Totterdell and Kylie Skipper who assisted and made data collection possible. We acknowledge David Whillas and Kevin Holden who operated the stereo-ROV on the pipelines. The contributions of Laura Fullwood and Damon Driessen both in the field and with image analysis are gratefully acknowledged, as is Jack Park for his assistance with image analysis. This research project was funded by Chevron through its Anchor Partnership with the UK National Decommissioning Centre. We also acknowledge in-kind support from Net Zero Technology Centre and the University of Aberdeen through their partnership in the UK National Decommissioning Centre.Peer reviewedPublisher PD

Skeletonized internal thoracic artery harvesting reduces chest wall dysesthesia after coronary bypass surgery

ObjectiveA pain syndrome related to intercostal nerve injury during internal thoracic artery harvesting causes significant morbidity after coronary bypass surgery. We hypothesized that its incidence and severity might be reduced by using skeletonized internal thoracic artery harvesting rather than pedicled harvesting.MethodsIn a prospective double-blind clinical trial, 41 patients undergoing coronary bypass were randomized to receive either unilateral pedicled or skeletonized internal thoracic artery harvesting. Patients were assessed 7 (early) and 21 (late) weeks postoperatively with reproducible sensory stimuli used to detect chest wall sensory deficits (dysesthesia) and with a pain questionnaire used to assess neuropathic pain.ResultsAt 7 weeks postoperatively, the area of harvest dysesthesia (percentage of the chest) in the skeletonized group (n = 21) was less (median, 0%; interquartile range, 0–0) than in the pedicled group (n = 20) (2.8% [0–13], P = .005). The incidence of harvest dysesthesia at 7 weeks was 14% in the skeletonized group versus 50% in the pedicled group (P = .02). These differences were not sustained at 21 weeks, as the median area of harvest dysesthesia in both groups was 0% (P = .89) and the incidence was 24% and 25% in the skeletonized and pedicled groups, respectively (P = 1.0). The incidence of neuropathic pain in the skeletonized group compared with the pedicled group was 5% versus 10% (P = .6) at 7 weeks and 0% versus 0% (P = 1.0) at 21 weeks.ConclusionsCompared with pedicled harvesting, skeletonized harvesting of the internal thoracic artery provides a short-term reduction in the extent and incidence of chest wall dysesthesia after coronary bypass, consistent with reduced intercostal nerve injury and therefore the reduced potential for neuropathic chest pain

BETANCOR, DIEGO [Material gráfico]

Copia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201