Search results for "Computer-aided"
showing 10 items of 416 documents
Computationally Efficient Analysis of Microwave Injection-Locked Amplifiers
2011
In this paper, some preliminary results on a novel approach to the analysis of injection-locked amplifiers are presented. The proposed method is based on a behavioral block modeling of the circuit in the fundamental-frequency dynamical phasor domain. The first-order exact perturbation refined treatment developed provides, in the end, explicit equations describing the entrained oscillation amplitude and phase dynamics. A secondary simplification then can be adopted in case of low-level injection, to determine a closed form expression for the locking bandwidth, generalizing the well known Adler’s one. By virtue of its semi-analytical nature, the proposed approach turns out to be much more eff…
Analysis of Bias-Shift Effects in Free-Running and Injection-Locked Negative Resistance Oscillators
2012
In this paper, the interaction between DC and RF in quasi-sinusoidal free-running and injection-locked oscillators is addressed. To account for and illustrate in a user-friendly manner the bias-shift related effects stemming from such interaction, a frequency-domain method of analysis has been developed for a rather wide class of negative-resistance circuits. Grounding on a first-approximation exact perturbation-refined approach, it permits computationally efficient simulation of the oscillator behavior directly in terms of the DC and RF signals evolutions (dynamical complex envelopes). In fact, it allows the investigation of both steady-state and transient operation of the shifting-bias dr…
Augmenting CASE tools with hypertext: Desired functionality and implementation issues
1997
Information systems have become bigger and more complex as their support has expanded to cover larger business domains, communication and work. At the same time technical design options such as client/server architectures and graphical user interfaces have increased the size and complexity of applications. In addition, pressures to build better systems more quickly have motivated the use of integrated design environments, such as CASE. Several integration approaches such as process modeling, frameworks and hypertext technology have been proposed. Of these we consider the least analyzed, hypertext technology, in this paper. Because of the novelty of hypertext in CASE there are several unreso…
VisAdapt: A Visualization Tool to Support Climate Change Adaptation.
2017
In this article we present the design and implementation of the web-based visualization tool VisAdapt, developed to support homeowners in the Nordic countries to assess anticipated climate change and climate related risks which are expected to negatively impact their living conditions. The tool guides the user through a three-step visual exploration process to facilitate the exploration of risks and adaptation measures, specifically adapted to the user. VisAdapt has been developed over the course of two years in close collaboration with domain experts and end users to ensure the validity of the included data and the efficiency of the visual interface. Although VisAdapt is designed for Nordi…
Molecular dynamics, dynamic site mapping, and highthroughput virtual screening on leptin and the Ob receptor as anti-obesity target.
2014
Body weight control is a mechanism finely regulated by several hormonal, metabolic, and nervous pathways. The leptin receptor (Ob-R) is crucial for energy homeostasis and regulation of food uptake. Leptin is a 16 kDa hormone that is mainly secreted by fat cells into the bloodstream, and under normal circumstances, circulating levels are proportionate to the fat body mass. Sensing of elevated leptin levels by the hypothalamic neurocircutry activates a negative feedback loop resulting in reduced food intake and increased energy expenditure. Decreased concentrations lead to opposite effects. Therefore rational design of leptin agonists constitute an appealing challenge in the battle against ob…
Review on Machine Learning Based Lesion Segmentation Methods from Brain MR Images
2016
Brain lesions are life threatening diseases. Traditional diagnosis of brain lesions is performed visually by neuro-radiologists. Nowadays, advanced technologies and the progress in magnetic resonance imaging provide computer aided diagnosis using automated methods that can detect and segment abnormal regions from different medical images. Among several techniques, machine learning based methods are flexible and efficient. Therefore, in this paper, we present a review on techniques applied for detection and segmentation of brain lesions from magnetic resonance images with supervised and unsupervised machine learning techniques.
A decade of research into player communities in online games
2013
The social dynamics of player communities in online games have been the subject of much research during the last decade. Following a systematic review of empirical research publications from 2000–2010, this article synthesizes the key methods and concepts researchers have used to study and characterize player communities. It also synthesizes the key aspects and operationalizations researchers have concentrated on. The analysis shows that qualitative approaches have been more common than quantitative ones. The concepts used to characterize player communities were often not clearly defined or overlapped in meaning. Yet they revealed a prevalence of micro (groups or teams), meso (guilds or org…
A collaborative virtual reality environment for liver surgery planning
2021
Abstract Surgical planning software is a key component in the treatment of tumor diseases. However, desktop-based systems provide only limited visualization and interaction opportunities. Moreover, collaborative planning among members of a surgical team is only possible to a limited extent. In this work, a collaborative virtual reality (VR) environment to assist liver surgeons in tumor surgery planning is presented. Our aim is to improve virtual resection planning between surgeons in a remote or co-located environment. The system allows surgeons to define and adjust virtual resections on patient-specific organ 3D surfaces and 2D image slices. Changes on both modalities are synchronized, whi…
Automatic segmentation and 3D reconstruction of intravascular ultrasound images for a fast preliminar evaluation of vessel pathologies.
2007
Abstract Intravascular ultrasound (IVUS) imaging is used along with X-ray coronary angiography to detect vessel pathologies. Manual analysis of IVUS images is slow and time-consuming and it is not feasible for clinical purposes. A semi-automated method is proposed to generate 3D reconstructions from IVUS video sequences, so that a fast diagnose can be easily done, quantifying plaque length and severity as well as plaque volume of the vessels under study. The methodology described in this work has four steps: a pre-processing of IVUS images, a segmentation of media–adventitia contour, a detection of intima and plaque and a 3D reconstruction of the vessel. Preprocessing is intended to remove …
MULTI-SCALE ANALYSIS OF LUNG COMPUTED TOMOGRAPHY IMAGES
2007
A computer-aided detection (CAD) system for the identification of lung internal nodules in low-dose multi-detector helical Computed Tomography (CT) images was developed in the framework of the MAGIC-5 project. The three modules of our lung CAD system, a segmentation algorithm for lung internal region identification, a multi-scale dot-enhancement filter for nodule candidate selection and a multi-scale neural technique for false positive finding reduction, are described. The results obtained on a dataset of low-dose and thin-slice CT scans are shown in terms of free response receiver operating characteristic (FROC) curves and discussed.