Deep submicron CMOS based on silicon germanium technology

The advantages to be gained by using SiGe in CMOS technology are examined, Conventional MOSFETs are compared with SiGe heterojunction MOSFETs suitable for CMOS technology and having channel lengths between 0.5 and 0.1 μm. Two-dimensional computer simulation demonstrates that the improved mobility in the SiGe devices, due to higher bulk mobility and the elimination of Si/SiO₂ interface scattering by the inclusion of a capping layer, results in significant velocity overshoot close to the source-end of the channel. The cut-off frequency, f_t , is found to increase by around 50% for n-channel devices while more than doubling for p-channel devices for typical estimates of mobility. The results offer the prospect of a more balanced CMOS and improved circuit speed especially when using dynamic logic     

Measurement and modeling of self-heating in SOI nMOSFET's

Self-heating in SOI nMOSFET's is measured and modeled. Temperature rises in excess of 100 K are observed for SOI devices under static operating conditions. The measured temperature rise agrees well with the predictions of an analytical model and is a function of the silicon thickness, buried oxide thickness, and channel-metal contact separation. Under dynamic circuit conditions, the channel temperatures are much lower than predicted from the static power dissipation. This work provides the foundation for the extraction of device modeling parameters for dynamic operation (at constant temperature) from static device characterization data (where temperature varies widely). Self-heating does not greatly reduce the electromigration reliability of SOI circuits, but might influence SOI device design, e.g., requiring a thinner buried oxide layer for particular applications and scaled geometries     

A Multiagent Platform for Ubiquitous Service Provision

The Virtual Home Environment is very important in contemporary mobile telecommunications infrastructure as it caters for the ubiquitous provision of services irrespective of network, location and user device. The universality of systems like Universal Mobile Telecommunications System and wi-fi increases the need for the rapid introduction of efficient VHE schemes. In this paper, we study the adoption of Mobile Agents for handling the VHE functionality. Mobile agents are nicely harmonized with the broader idea of VHE as they allow the autonomous execution of tasks by components that roam from node to node and network to network. We present the detailed modeling of a VHE provisioning architecture and investigate its suitability for different use cases and technical options (e.g., end user devices). The adoption of mobile agents for the ubiquitous provision of telecommunication services is quite promising in terms of efficiency. Through a series of experiments we quantify the performance benefits stemming from the adoption of mobile agents in contrast to conventional service provisioning schemes.     

Application of the digital signal processing methodology (DSPM) for the design of time integration formulae

Although the existence of a close relationship between the areas of digital processing and time integration methodology has been established long ago, only recently a systematic application of the concepts and methods of the first area to the second has been attempted. The resulting Digital Signal Processing Methodology is applied in this paper to demostrate that time integration methods can be designed, displaying advanced performance in the computational analysis of large complex systems, with respect to accuracy, spurious oscillations damping, overshooting and asymptotic behavior for singular cases.     

Parsing human skeletons in an operating room

Multiple human pose estimation is an important yet challenging problem. In an operating room (OR) environment, the 3D body poses of surgeons and medical staff can provide important clues for surgical workflow analysis. For that purpose, we propose an algorithm for localizing and recovering body poses of multiple human in an OR environment under a multi-camera setup. Our model builds on 3D Pictorial Structures and 2D body part localization across all camera views, using convolutional neural networks (ConvNets). To evaluate our algorithm, we introduce a dataset captured in a real OR environment. Our dataset is unique, challenging and publicly available with annotated ground truths. Our proposed algorithm yields to promising pose estimation results on this dataset.     

Statistical Analysis and Modeling of Jobs in a Grid Environment

The existence of good probabilistic models for the job arrival process and the delay components introduced at different stages of job processing in a Grid environment is important for the improved understanding of the Grid computing concept. In this study, we present a thorough analysis of the job arrival process in the EGEE infrastructure and of the time durations a job spends at different states in the EGEE environment. We define four delay components of the total job delay and model each component separately. We observe that the job inter-arrival times at the Grid level can be adequately modelled by a rounded exponential distribution, while the total job delay (from the time it is generated until the time it completes execution) is dominated by the computing element’s register and queuing times and the worker node’s execution times. Further, we evaluate the efficiency of the EGEE environment by comparing the job total delay performance with that of a hypothetical ideal super-cluster and conclude that we would obtain similar performance if we submitted the same workload to a super-cluster of size equal to 34% of the total average number of CPUs participating in the EGEE infrastructure. We also analyze the job inter-arrival times, the CE’s queuing times, the WN’s execution times, and the data sizes exchanged at the kallisto.hellasgrid.gr cluster, which is node in the EGEE infrastructure. In contrast to the Grid level, we find that at the cluster level the job arrival process exhibits self-similarity/long-range dependence. Finally, we propose simple and intuitive models for the job arrival process and the execution times at the cluster level.     

Optimizations of the naïve-Bayes classifier for the prognosis of B-Chronic Lymphocytic Leukemia incorporating flow cytometry data

Prognosis of B-Chronic Lymphocytic Leukemia (B-CLL) remains a challenging problem in medical research and practice. While the parameters obtained by flow cytometry analysis form the basis of the diagnosis of the disease, the question whether these parameters offer additional prognostic information still remains open. In this work, we attempt to provide computer-assisted support to the clinical experts of the field, by deploying a classification system for B-CLL multiparametric prognosis that combines various heterogeneous (clinical, laboratory and flow cytometry) parameters associated with the disease. For this purpose, we employ the na?ve-Bayes classifier and propose an algorithm that improves its performance. The algorithm discretizes the continuous classification attributes (candidate prognostic parameters) and selects the most useful subset of them to optimize the classification accuracy. Thus, in addition to the high classification accuracy achieved, the proposed approach also suggests the most informative parameters for the prognosis. The experimental results demonstrate that the inclusion of flow cytometry parameters in our system improves prognosis.     

Estimating spine shape in lateral sleep positions using silhouette-derived body shape models

This study aims at evaluating spinal alignment during sleep by combining personalized human models with mattress indentation measurements. A generic surface model has been developed that can be personalized based on anthropometric parameters derived from silhouette extraction. Shape assessment of the personalized surface models, performed by comparison with 3-D surface scans of the trunk, showed a mean unsigned distance of 9.77 mm between modeled and scanned surface meshes. The surface model is combined with an inner skeleton model, allowing the model to simulate distinct sleep postures. An automatic fitting algorithm sets the appropriate degrees of freedom to position the model on the measured indentation according to the adopted sleep posture. Validation on lateral sleep positions showed good intraclass correlations (0.73–0.88) between estimated and measured angular spinal deformations, indicating that silhouette-derived body shape models provide a valuable tool for the unobtrusive assessment of spinal alignment during sleep.Relevance to industry: A common drawback of the available techniques to assess spinal deformation on bedding systems is that they interfere with the actual sleep process. The current study presents a novel method based on silhouette-derived body shape models in order to estimate spine shape during sleep unobtrusively.     

Mapping and classification of direct flood impacts in the complex conditions of an urban environment. The case study of the 2014 flood in Athens,Greece

Urban flooding is a gradually increasing problem as the urban population expands into floodplains. In urban environments, flood vulnerability is significantly increased as a more concentrated population and assets makes flooding costly and challenging, in terms of impact estimation. This work focuses on mapping and classifying impacts after the catastrophic 2014 flood in Athens, Greece. The study proposes a method for classifying flood effects into four categories including: the natural and built environment, mobile objects and human population, organized in five classes of increasing severity, i.e. minor, weak, moderate, strong and extreme. Flood effects are grouped based on the qualitative nature of the recorded effects, allowing the development of an impact-severity map. Mapping of the 2014 flood effects indicated specific locations where the severity of impacts was distinctively higher than others, providing a holistic overview of the flood’s effects and highlighting the usefulness of the approach in future flood protection planning.