Pervasive Computing

This book provides a concise introduction to Pervasive Computing, otherwise known as Internet of Things (IoT) and Ubiquitous Computing (Ubicomp) which addresses the seamless integration of computing systems within everyday objects. By introducing the core topics and exploring assistive pervasive systems which infer their context through pattern recognition, the author provides readers with a gentle yet robust foundation of knowledge to this growing field of research. The author explores a range of topics including data acquisition, signal processing, control theory, machine learning and system engineering explaining, with the use of simple mathematical concepts, the core principles underlying pervasive computing systems. Real-life examples are applied throughout, including self-driving cars, automatic insulin pumps, smart homes, and social robotic companions, with each chapter accompanied by a set of exercises for the reader. Practical tutorials are also available to guide enthusiastic readers through the process of building a smart system using cameras, microphones and robotic kits. Due to the power of MATLAB™, this can be achieved with no previous programming or robotics experience. Although Pervasive Computing is primarily for undergraduate students, the book is accessible to a wider audience of researchers and designers who are interested in exploring pervasive computing further

Electron Beam Induced Nanometer Scale Deposition

Applied Science

Using a systems-theoretic approach to analyze safety in radiation therapy-first steps and lessons learned

Radiation therapy is an important technique to treat cancer. Due to the high occupational risks involved, the process is subject to severe safety regulations and standards. However, these standards do not mandate the usage of a particular hazard analysis method. The de facto methods currently used are the reliability theory-based Fault Tree Analysis (FTA) and Healthcare Failure Mode and Effects Analysis (HFMEA). Systems Theoretic Process Analysis (STPA) is a new, essentially different hazard analysis method, based on systems theory. Although successfully applied in many industries, there are only a few reports on STPA implementation in radiation therapy. This paper contributes to filling this gap with a preliminary assessment of STPA applied to a mature Intensity Modulated Radiation Therapy (IMRT) process. The analysis was conducted by a team consisting of two experts in radiation therapy and one software systems engineer, with little domain knowledge. 142 potentially unsafe control actions were identified and compared with the results of an earlier HFMEA. The main lesson we have learned is that a graphical, system-wise modeling of the analyzed process, although challenging for beginners, is a powerful instrument to catch the same and even other, new hazards. A causal analysis of a subset of these newly found hazards has led to meaningful and valuable risk mitigation measures. These results suggest considering STPA as a viable option for safety analysis in radiation therapy. We expect that this top-down, well-structured way of analysis can especially be advantageous for safety assessment in early design phases, when an HFMEA is not possible yet, because most of system's implementation and behavior is still unknown

Direct fabrication of nanowires in an electron microscope

Electron-beam-induced deposition (EBID) is a potentially fast and resistless deposition technique which might overcome the fundamental resolution limits of conventional electron-beam lithography. We advance the understanding of the EBID process by simulating the structure growth. The merit of our model is that it explains the shapes of structures grown by EBID quantitatively. It also predicts the possibility to directly fabricate structures with lateral sizes smaller than 10 nm and points out the ideal conditions to achieve this goal. We verify these predictions by fabricating sub-10-nm lines and dots in a state-of-the-art scanning transmission electron microscope.Imaging Science and TechnologyApplied Science

Spatial resolution limits in electron-beam-induced deposition

Electron-beam-induced deposition (EBID) is a versatile micro- and nanofabrication technique based on electron-induced dissociation of metal-carrying gas molecules adsorbed on a target. EBID has the advantage of direct deposition of three-dimensional structures on almost any target geometry. This technique has occasionally been used in focused electron-beam instruments, such as scanning electron microscopes, scanning transmission electron microscopes (STEM), or lithography machines. Experiments showed that the EBID spatial resolution, defined as the lateral size of a singular deposited dot or line, always exceeds the diameter of the electron beam. Until recently, no one has been able to fabricate EBID features smaller than 15–20?nm diameter, even if a 2-nm-diam electron-beam writer was used. Because of this, the prediction of EBID resolution is an intriguing problem. In this article, a procedure to theoretically estimate the EBID resolution for a given energetic electron beam, target, and gaseous precursor is described. This procedure offers the most complete approach to the EBID spatial resolution problem. An EBID model was developed based on electron interactions with the solid target and with the gaseous precursor. The spatial resolution of EBID can be influenced by many factors, of which two are quantified: the secondary electrons, suspected by almost all authors working in this field, and the delocalization of inelastic electron scattering, a poorly known effect. The results confirm the major influence played by the secondary electrons on the EBID resolution and show that the role of the delocalization of inelastic electron scattering is negligible. The model predicts that a 0.2-nm electron beam can deposit structures with minimum sizes between 0.2 and 2?nm, instead of the formerly assumed limit of 15–20?nm. The modeling results are compared with recent experimental results in which 1-nm?W dots from a W(CO)6 precursor were written in a 200-kV STEM on a 30-nm SiN membrane.Imaging Science and TechnologyApplied Science