Analytic formulation of the response of a two-wire transmissionline excited by a plane wave

A perfectly conducting uniform two-wire transmission line of finite length illuminated by a plane wave is considered. The induced voltage and current-responses are described by analytic expressions in the frequency and time domains. Moreover, an instructive case study is presented. This simplified and cost effective method can be an important part of the theoretical NEMP-analysis of systems     

Determination of hot crack susceptibility in various kinds of steels

The aim of this investigation was to study the hot crack susceptibility of some Turkish and German structural steel plates with a modified varestraint-transvarestraint test method. Testing was accomplished using a Tungsten Inert Gas (TIG) welding process. The results of this study revealed that total crack length increases as welding current increases or punch radius or welding speed decreases. An attempt is made to provide explanations for these phenomena.     

Grey-box modeling of an ocean vessel for operational optimization

Operational optimization of ocean vessels, both off-line and in real-time, is becoming increasingly important due to rising fuel cost and added environmental constraints. Accurate and efficient simulation models are needed to achieve maximum energy efficiency. In this paper a grey-box modeling approach for the simulation of ocean vessels is presented. The modeling approach combines conventional analysis models based on physical principles (a white-box model) with a feed forward neural-network (a black-box model). Two different ways of combining these models are presented, in series and in parallel. The results of simulating several trips of a medium sized container vessel show that the grey-box modeling approach, both serial and parallel approaches, can improve the prediction of the vessel fuel consumption significantly compared to a white-box model. However, a prediction of the vessel speed is only improved slightly. Furthermore, the results give an indication of the potential advantages of grey-box models, which is extrapolation beyond a given training data set and the incorporation of physical phenomena which are not modeled in the white-box models. Finally, included is a discussion on how to enhance the predictability of the grey-box models as well as updating the neural-network in real-time.     

Degree of polarization in tightly focused optical fields

We analyze the degree of polarization of random, statistically stationary electromagnetic fields in the focal region of a high-numerical-aperture imaging system. The Richards-Wolf theory for focusing is employed to compute the full 3 x 3 electric coherence matrix, from which the degree of polarization is obtained by using a recent definition for general three-dimensional electromagnetic waves. Significant changes in the state of partial polarization, compared with that of the incident illumination, are observed. For example, a wave consisting of two orthogonal and uncorrelated incident-electric-field components produces rings of full polarization in the focal plane. These effects are explained by considering the distribution of the spectral densities of the three electric field components as well as the correlations between them.     

Thionine-interlinked multi-walled carbon nanotube/gold nanoparticle composites

Multi-walled carbon nanotube (MWCNT)/thionine/gold nanoparticle composites were prepared by binding gold nanoparticles to the surfaces of thionine-coated carbon nanotubes. TEM images show gold nanoparticles distributed uniformly on nanotube walls and ends. UV-Vis, Raman, FT-IR, and zeta potential measurements were used to examine the properties of the resulting products. The composites demonstrate significant electrocatalytic activity for oxygen reduction. Although only gold nanoparticles were investigated here, the method could be easily extended to attach other metallic nanoparticles to the sidewalls of carbon nanotubes.     

Very long term success of pterygium surgery with conjunctival graft

Purpose

To examine to the very long term prognosis (16 years in average) of pterygium surgery with superior or inferior conjunctival graft.

Hybrid Wireless Sensors Deployment Scheme with Connectivity and Coverage Maintaining in Wireless Sensor Networks

With the rapid growth of the internet of things (IoT), an impressive number of IoT’s application based on wireless sensor networks (WSNs) has been deployed in various domain. Due to its wide ranged applications, WSNs that have the capability to monitor a given sensing field, became the most used platform of IoT. Therefore, coverage becomes one of the most important challenge of WSNs. The search for better positions to assign to the sensors in order to control each point of an area of interest and the collection of data from sensors are major concerns in WSNs. This work addresses these problems by providing a hybrid approach that ensures sensors deployment on a grid for targets coverage while taking into account connectivity. The proposed sequential hybrid approach is based on three algorithms. The first places the sensors so as to all targets are covered. The second removes redundancies from the placement algorithm to reduce the number of sensors deployed. The third one, based on the genetic algorithm, aims to generate a connected graph which provide a minimal path that links deployed sensors and sink. Simulations and a comparative study were carried out to prove the relevance of the proposed method.

     

Adoption barriers of network layer protocols: The case of host identity protocol

With increasing societal dependence on the Internet and new application areas emerging, the need for securing communications and identifying communication partners is expected to increase. However, the original Internet architecture is lacking these functionalities, and most of the protocols proposed to fix these issues have not been widely deployed. Often one of the reasons for such failure is that protocol designers have insufficient understanding of the potential adopters’ economic incentives so one may end up designing protocols based on false or inaccurate assumptions. In this paper, we analyze the Host Identity Protocol (HIP) from this viewpoint. Based on 19 expert interviews, we identify six main reasons why HIP has not been widely deployed yet. Most importantly, (1) the demand for the functionalities of HIP has been low. Where demand would have existed, substitute solutions have been favored because (2) they were earlier on the market, (3) they have relative advantage due to some design choices of HIP, (4) HIP lacks early adopter benefits necessitating costly coordination among multiple stakeholders in public deployment scenarios, and (5) people have misconceptions about the deployability of HIP. Additionally, (6) the research-mindedness of HIP developers has lead to strategic mistakes and non-optimal design choices from the perspective of deployment. We also suggest strategies that HIP developers could take to foster the adoption of HIP. Besides providing value to HIP developers, the results propose some new adoption barriers and deployment strategies that could be taken into account when designing new protocols. Finally, the article also provides a template that could be followed when studying the feasibility of other protocols.     

Hierarchical Architecture for Multi-Technology Wireless Sensor Networks for Critical Infrastructure Protection

A hierarchical architecture for wireless sensor network (WSN) consisting of heterogeneous devices is introduced in this paper. Proposed architecture is well suited for surveillance of critical infrastructures and it is designed to be scalable for various different scenarios. Low power consumption will be achieved by utilizing a wake-up radio concept which enables to keep the most power consuming devices at the sleep mode as long as possible. A WSN OpenAPI gateway (WOAG) component of the architecture supports high scalability by enabling data collection and sharing from networks deployed using multiple different technologies. WOAG facilitates WSNs information availability to local and remote end-users. Analytical energy efficiency optimization model for the architecture is developed. Results show energy efficiency gains that can be achieved with the proposed wake-up concept based intelligent hierarchical architecture design. For low event frequency case the energy efficiency is found to be one order of magnitude better than for duty cycle (1 %) radio based network.     

In search of an optimization technique for Artificial Neural Network to classify abnormal heart sounds

Artificial Neural Network (ANN) finds use in classification of heart sounds for its discriminative training ability and easy implementation. The selection of number of nodes for an ANN remains an important issue as an overparameterized ANN gets trained along with the redundant information that results in poor validation. Also a larger network means more computational expense, resulting more hardware and time related cost. Therefore, a compact and optimum design of neural network is needed towards real-time detection of pathological patterns, if any from heart sound signals. This work attempts to (i) design a compact form of output layer with less number of nodes than output classes, (ii) select a set of input features that are effective for identification of heart sound signals using Singular Value Decomposition (SVD), QR factorization with column pivoting (QRcp) and Fisher's F-ratio, (iii) make certain optimum selection of nodes in the hidden layer for a more effective ANN structure using SVD and (iv) select and prune weights based on the concept of local relative sensitivity index (LRSI) for empirically chosen overparameterized ANN structure for phonocardiogram (PCG) classification. It is observed that the proposed techniques perform better in terms of reduction of model residues and time complexity for classifying 12 different pathological cases and normal heart sound.