Clifford De Raffaele

Thermographic Patterns of the Upper and Lower Limbs: Baseline Data

Objectives. To collect normative baseline data and identify any significant differences between hand and foot thermographic distribution patterns in a healthy adult population. Design. A single-centre, randomized, prospective study. Methods. Thermographic data was acquired using a FLIR camera for the data acquisition of both plantar and dorsal aspects of the feet, volar aspects of the hands, and anterior aspects of the lower limbs under controlled climate conditions. Results. There is general symmetry in skin temperature between the same regions in contralateral limbs, in terms of both magnitude and pattern. There was also minimal intersubject temperature variation with a consistent temperature pattern in toes and fingers. The thumb is the warmest digit with the temperature falling gradually between the 2nd and the 5th fingers. The big toe and the 5th toe are the warmest digits with the 2nd to the 4th toes being cooler. Conclusion. Measurement of skin temperature of the limbs using a thermal camera is feasible and reproducible. Temperature patterns in fingers and toes are consistent with similar temperatures in contralateral limbs in healthy subjects. This study provides the basis for further research to assess the clinical usefulness of thermography in the diagnosis of vascular insufficiency.

Modeling electromagnetic interference generated by a WLAN system onboard commercial aircraft

The growing demand for the utilization of personal electronic communication devices onboard commercial aircraft necessitates the assurance of safety by airline operators and regulators. This implies that the potential risks posed by the deployment of wireless communication systems on critical aircraft equipment must be carefully assessed and countermeasures taken when required. In this paper, a model based on a ray-tracing algorithm is developed to calculate the electromagnetic interference incident on the fuselage structure of a commercial airline. The source of interference is a 2.4 GHz data communications network. Two scenarios are considered; the first assumes a base station in the centre of the cabin while the second considers four base stations, transmitting at a lower power, distributed along the cabin. The model first determines the propagation map generated by the base stations. These results are used to establish the transmission power required by the personal mobile devices which is then employed to determine the propagation map of each device. The overall electromagnetic interference map incident on the fuselage resulting from the onboard wireless network is generated by vectorially combining the resulting

Efficient multiview depth representation based on image segmentation

The persistent improvements witnessed in multimedia production have considerably augmented users demand for immersive 3D systems. Expedient implementation of this technology however, entails the need for significant reduction in the amount of information required for representation. Depth image-based rendering algorithms have considerably reduced the number of images necessary for 3D scene reconstruction, nevertheless the compression of depth maps still poses several challenges due to the peculiar nature of the data. To this end, this paper proposes a novel depth representation methodology that exploits the intrinsic correlation present between colour intensity and depth images of a natural scene. A segmentation-based approach is implemented which decreases the amount of information necessary for transmission by a factor of 24 with respect to conventional JPEG algorithms whilst maintaining a quasi identical reconstruction quality of the 3D views.

Small aircraft cockpit electromagnetic interference due to UMTS signal propagation

This paper implemented a ray-tracing based algorithm to calculate the EMI generated inside an aircraft cabin with particular emphasis on flight critical equipment such as the cockpit avionics panel. The interference level caused by the deployment of a UMTS Node B antenna for the provision of passenger communication was computed. The model was employed to study the effects of the multipath electromagnetic propagation attained from positioning a Node B antenna in different locations inside a relatively small tunnel shaped fuselage with dense furnishings. The proposed framework is also able to provide an all-encompassing understanding of the generated EMI, whilst offering support for the development of conscientious network design in aircraft.

Applying Prediction Techniques to Reduce Uplink Transmission and Energy Requirements in Mobile Free-Viewpoint Video Applications

The increased efficiency of video compression algorithms, the improvements registered in reliability, data rates and quality of service of wireless transmission technologies, and the development of mobile multimedia terminals have made possible the implementation of Free-Viewpoint Video (FVV) technology on mobile platforms. The mobile environment however presents several restrictions. Two of these limiting factors being bandwidth constraints and energy availability in battery-operated mobile terminals. This paper looks at the possibility of employing prediction algorithms at the FVV server to anticipate the next viewpoint expected by the user. In doing so, the number of uplink requests is reduced to situations where the estimated view defers from the requested one and the associated transmissions required in retraining the algorithm once this occurs. Simulation results on two different prediction techniques demonstrate that the uplink transmission rate is reduced by up to 96.7% when emulating a conventional FVV usage scenario. Both prediction algorithms infer a substantial decrease in the mobile terminal’s power consumption and reduce the network’s uplink bandwidth utilization.

Minimizing Uplink Data in Wireless Free-Viewpoint Video Transmission Applications

The increase in processing power of mobile multimedia terminals, the improvements in camera technology and efficient video compression algorithms have made the implementation of mobile Free-Viewpoint Video (FVV) technology possible. However, the use of this technology in wireless environments poses a number of challenges. Amongst these there are issues in bandwidth utilisation and the limited supply power of the mobile device. To this effect, this paper compares the implementation of two prediction algorithms to forecast the next viewpoint in an attempt to minimise the amount of viewpoint requests uploaded to the server. Simulation results demonstrate that a reduction of up to 72% in uplink transmission traffic is achieved when emulating a conventional usage scenario. This means that the application of prediction schemes can drastically reduce the power consumption and resource requirements of mobile multimedia terminals.

Performance improvement of segmentation-based depth representation in 3D imagery by region merging

The feasible implementation of immersive 3D video systems entails the need for a substantial reduction in the amount of image information necessary for representation. Multiview image rendering algorithms based on depth data have radically reduced the number of images required to reconstruct a 3D scene. Nonetheless, the compression of depth maps still poses several challenges due to the particular nature and characteristics of the data. To this end, this paper outlines a depth representation technique, developed in our earlier work, that exploits the correlation intrinsically present between color intensity and depth images capturing a natural scene. In this technique, a segmentation-based algorithm that is backwards compatible with conventional video coding systems is implemented. The effectiveness of our previous technique is enhanced in this contribution by a region merging process on the segmented regions, which results in a decrease in the amount of information necessary for transmission or storage of multiview image data by a factor of 20.5 with respect to the reference H.264/AVC coding methodology. This is furthermore achieved whilst maintaining a 3D image reconstruction and viewing quality which is quasi identical to the referenced approach.

Modeling Electromagnetic signal levels falling on aircraft from satellite communication systems

The persistent growth in demand for broadband communication services has lead to the widespread deployment of high-frequency Ka-Band satellite communication systems. This phenomenon however, presents a scenario whereby aircraft in mid-flight are evermore subjected to a diversity of external high frequency signals. The latter can potentially generate Electromagnetic Interference (EMI) with the communications and control avionic systems onboard the aircraft. These drastic effects are becoming increasingly noteworthy, and the aircraft industry is progressively seeking more thorough electromagnetic compatibility assessments prior to aircraft manufacture.12

Simulating electromagnetic field inside small aircraft from wireless camera equipment

The proliferation of wireless systems has urged the aviation industry to consider the exploitation of such a technology to introduce new services and to curtail its cabling weight requirements. Nevertheless, prior to implementing such communication systems, manufactures must ensure that the paramount criterion of aircraft safety is unaffected and thus the potential electromagnetic (EM) field posed on aircraft equipment must be carefully assessed and respective countermeasures taken. To this end, this paper adopts a frequency-domain based three-dimensional ray tracing algorithm, based on geometrical optics to compute the EM field generated from the use of wireless camera equipment transmitting at 2.4 GHz inside the cabin of a typical business jet. The model comprehensively considers the various propagation methodologies utilized by multipath signals to provide a holistic understanding of the resultant average field strength incident at each location inside the fuselage.