Social Diffusion Patterns in Three-Dimensional Virtual Worlds

2003 ◽  
Vol 2 (3) ◽  
pp. 182-198 ◽  
Author(s):  
Katy Börner ◽  
Shashikant Penumarthy
Keyword(s):  
Virtual Worlds ◽  
Three Dimensional ◽  
Simulated Data ◽  
Visualization Tool ◽  
Group Leaders ◽  
Real World Data ◽  
User Groups ◽  
Tool Set ◽  
Future Work ◽  
And Diffusion

This paper presents a visualization tool set that can be used to visualize the evolution of three-dimensional (3D) virtual environments, the distribution of their virtual inhabitants over time and space, the formation and diffusion of groups, the influence of group leaders, and the environmental and social influences on chat and diffusion patterns for small (1 – 100 participants) but also rather large user groups (more than 100 participants). The techniques are applied to analyze and visualize data recorded during events in virtual worlds, as well as simulated data, but are also applicable to real-world data. Resulting visualizations can and have been used to ease social navigation in 3D virtual worlds, help evaluate and optimize the design of virtual worlds, and provide a means to study the communities evolving in virtual worlds. The visualizations are particularly valuable for analyzing events that are spread out in time and/or space or events that involve a very large number of participants. The paper reviews and builds upon research in information visualization, scientific visualization, geography, architecture, and social science. It discusses intended user groups and their tasks and how the proposed techniques support those tasks. Three dimensional virtual world technologies are briefly described before the visualization tool set is explained in detail together with sample applications. The paper concludes with a discussion of results and an outlook for future work.

scholarly journals Adaptive Chaotic Image Encryption Algorithm Based on RNA and Pixel Depth

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1770
Author(s):  
Xiaoqiang Zhang ◽  
Xuangang Yan
Keyword(s):  
Image Encryption ◽  
Three Dimensional ◽  
Encryption Algorithm ◽  
Current Time ◽  
Plain Image ◽  
Scope Of Application ◽  
Selective Diffusion ◽  
Chaotic Image Encryption ◽  
And Diffusion ◽  
Image Encryption Algorithm

To prevent the leakage of image content, image encryption technology has received increasing attention. Most current algorithms are only suitable for the images of certain types and cannot update keys in a timely manner. To tackle such problems, we propose an adaptive chaotic image encryption algorithm based on RNA and pixel depth. Firstly, a novel chaotic system, two-dimensional improved Logistic-adjusted-Sine map is designed. Then, we propose a three-dimensional adaptive Arnold transform for scrambling. Secondly, keys are generated by the hash values of the plain image and current time to achieve one-image, one-key, and one-time pad simultaneously. Thirdly, we build a pre-permuted RNA cube for 3D adaptive scrambling by pixel depth, chaotic sequences, and adaptive RNA coding. Finally, selective diffusion combined with pixel depth and RNA operations is performed, in which the RNA operators are determined by the chemical structure and properties of amino acids. Pixel depth is integrated into the whole procedure of parameter generation, scrambling, and diffusion. Experiments and algorithm analyses show that our algorithm has strong security, desirable performance, and a broader scope of application.

scholarly journals Improving the performance of a radio-frequency localization system in adverse outdoor applications

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Marcelo N. de Sousa ◽  
Ricardo Sant’Ana ◽  
Rigel P. Fernandes ◽  
Julio Cesar Duarte ◽  
José A. Apolinário ◽  
...  
Keyword(s):  
Random Forest ◽  
Ray Tracing ◽  
Real World ◽  
Practical Implication ◽  
Real Life ◽  
Simulated Data ◽  
Real Data ◽  
Gradient Boosting ◽  
Real World Data ◽  
Localization Accuracy

AbstractIn outdoor RF localization systems, particularly where line of sight can not be guaranteed or where multipath effects are severe, information about the terrain may improve the position estimate’s performance. Given the difficulties in obtaining real data, a ray-tracing fingerprint is a viable option. Nevertheless, although presenting good simulation results, the performance of systems trained with simulated features only suffer degradation when employed to process real-life data. This work intends to improve the localization accuracy when using ray-tracing fingerprints and a few field data obtained from an adverse environment where a large number of measurements is not an option. We employ a machine learning (ML) algorithm to explore the multipath information. We selected algorithms random forest and gradient boosting; both considered efficient tools in the literature. In a strict simulation scenario (simulated data for training, validating, and testing), we obtained the same good results found in the literature (error around 2 m). In a real-world system (simulated data for training, real data for validating and testing), both ML algorithms resulted in a mean positioning error around 100 ,m. We have also obtained experimental results for noisy (artificially added Gaussian noise) and mismatched (with a null subset of) features. From the simulations carried out in this work, our study revealed that enhancing the ML model with a few real-world data improves localization’s overall performance. From the machine ML algorithms employed herein, we also observed that, under noisy conditions, the random forest algorithm achieved a slightly better result than the gradient boosting algorithm. However, they achieved similar results in a mismatch experiment. This work’s practical implication is that multipath information, once rejected in old localization techniques, now represents a significant source of information whenever we have prior knowledge to train the ML algorithm.

Facilitating 3D Virtual World Learning Environments Creation by Non-Technical End Users through Template-Based Virtual World Instantiation

2013 ◽  
Vol 4 (1) ◽  
pp. 32-48 ◽  
Author(s):  
Chang Liu ◽  
Ying Zhong ◽  
Sertac Ozercan ◽  
Qing Zhu
Keyword(s):  
Learning Environments ◽  
Virtual Worlds ◽  
Virtual World ◽  
Three Dimensional ◽  
End Users ◽  
Preliminary Evaluation ◽  
3D Design ◽  
Domain Specific ◽  
Functional Learning ◽  
Preliminary Experimental Data

This paper presents a template-based solution to overcome technical barriers non-technical computer end users face when developing functional learning environments in three-dimensional virtual worlds (3DVW). iVirtualWorld, a prototype of a platform-independent 3DVW creation tool that implements the proposed solution, facilitates 3DVW learning environment creation through semantics-based abstract 3DVW representation and template-based 3DVW instantiation. iVirtualWorld provides a wizard to guide the 3DVW creation process, and hide low-level programming and 3D design details through higher-level abstracts supported by pre-defined templates. Preliminary evaluation of the effectiveness of iVirtualWorld showed positive results. The contribution of this study is threefold: 1) It provides a paradigm for investigating and developing 3DVW building tools from end users’ perspective; 2) It develops a prototype of a 3DVW building tool, which gives educators a framework to easily create educational virtual worlds using domain-specific concepts; 3) It conducts empirical research and collected preliminary experimental data for evaluation.

scholarly journals Second Life as a research environment: avatar-based focus groups (AFG)

2016 ◽  
Vol 19 (1) ◽  
pp. 101-114 ◽  
Author(s):  
Eman Gadalla ◽  
Ibrahim Abosag ◽  
Kathy Keeling
Keyword(s):  
Focus Groups ◽  
Data Quality ◽  
Virtual Worlds ◽  
Second Life ◽  
Three Dimensional ◽  
Marketing Research ◽  
Two Phase ◽  
Content Type ◽  
Face To Face ◽  
Advantages And Disadvantages

Purpose – This study aims to examine the nature and the potential use of avatar-based focus groups (AFGs) (i.e. focus groups conducted in three-dimensional [3D] virtual worlds [VWs]) as compared to face-to-face and online focus groups (OFGs), motivated by the ability of VWs to stimulate the realism of physical places. Over the past decade, there has been a rapid increase in using 3D VWs as a research tool. Design/methodology/approach – Using a two-phase reflective approach, data were collected first by using traditional face-to-face focus groups, followed by AFGs. In Phase 2, an online, semi-structured survey provided comparison data and experiences in AFGs, two-dimensional OFGs and traditional face-to-face focus groups. Findings – The findings identify the advantages and disadvantages of AFGs for marketing research. There is no evident difference in data quality between the results of AFGs and face-to-face focus groups. AFG compensates for some of the serious limitations associated with OFGs. Practical implications – The paper reflects on three issues, data quality, conduct of AFGs (including the moderator reflection) and participant experience, that together inform one’s understanding of the characteristics, advantages and limitations of AFG. Originality/value – This is the first paper to compare between AFGs, traditional face-to-face focus groups and OFGs. AFG holds many advantages over OFGs and even, sometimes, over face-to-face focus groups, providing a suitable environment for researchers to collect data.

scholarly journals How Stereological Analysis of Vascular Morphology Can Quantify the Blood Volume Fraction as a Marker for Tumor Vasculature: Comparison with Magnetic Resonance Imaging

2011 ◽  
Vol 32 (3) ◽  
pp. 489-501 ◽  
Author(s):  
Adriana T Perles-Barbacaru ◽  
Boudewijn PJ van der Sanden ◽  
Regine Farion ◽  
Hana Lahrech
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Rat Brain ◽  
Blood Volume ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Simulated Data ◽  
Tumor Model ◽  
Tumor Vasculature ◽  
Resonance Imaging

To assess angiogenesis noninvasively in a C6 rat brain tumor model, the rapid-steady-state- T1 (RSST1) magnetic resonance imaging (MRI) method was used for microvascular blood volume fraction (BVf) quantification with a novel contrast agent gadolinium per (3,6 anhydro) α-cyclodextrin (Gd-ACX). In brain tissue contralateral to the tumor, equal BVfs were obtained with Gd-ACX and the clinically approved gadoterate meglumine (Gd-DOTA). Contrary to Gd-DOTA, which leaks out of the tumor vasculature, Gd-ACX was shown to remain vascular in the tumor tissue allowing quantification of the tumor BVf. We sought to confirm the obtained tumor BVf using an independent method: instead of using a ‘standard’ two-dimensional histologic method, we study here how vascular morphometry combined with a stereological technique can be used for three-dimensional assessment of the vascular volume fraction ( VV). The VV is calculated from the vascular diameter and length density. First, the technique is evaluated on simulated data and the healthy rat brain vasculature and is then applied to the same C6 tumor vasculature previously quantified by RSST1-MRI with Gd-ACX. The mean perfused VV and the BVf obtained by MRI in tumor regions are practically equal and the technique confirms the spatial heterogeneity revealed by MRI.

Fast (non-)diffusive Quasi-Geostrophic Magneto-Coriolis Modes in the Earth's core

2021 ◽  
Author(s):  
Felix Gerick ◽  
Dominique Jault ◽  
Jerome Noir
Keyword(s):  
Magnetic Field ◽  
Magnetic Energy ◽  
Three Dimensional ◽  
Outer Core ◽  
Equatorial Region ◽  
Earth’S Core ◽  
Earth's Core ◽  
Strong Focusing ◽  
Geomagnetic Observations ◽  
And Diffusion

<p> Fast changes of Earth's magnetic field could be explained by inviscid and diffusion-less quasi-geostrophic (QG) Magneto-Coriolis modes. We present a hybrid QG model with columnar flows and three-dimensional magnetic fields and find modes with periods of a few years at parameters relevant to Earth's core. These fast Magneto-Coriolis modes show strong focusing of their kinetic and magnetic energy in the equatorial region, while maintaining a relatively large spatial structure along the azimuthal direction. Their properties agree with some of the observations and inferred core flows. We find additionally, in contrast to what has been assumed previously, that these modes are not affected significantly by magnetic diffusion. The model opens a new way of inverting geomagnetic observations to the flow and magnetic field deep within the Earth's outer core.</p>

scholarly journals Towards Continuous Production of Shaped Honeycombs

2018 ◽  
Author(s):  
Sam E. Calisch ◽  
Neil A. Gershenfeld
Keyword(s):  
High Performance ◽  
Continuous Production ◽  
Continuous Process ◽  
Three Dimensional ◽  
Sandwich Panels ◽  
Performance Space ◽  
Bending Loads ◽  
Future Work ◽  
The Impact ◽  
Parallel Folding

Honeycomb sandwich panels are widely used for high performance parts subject to bending loads, but their manufacturing costs remain high. In particular, for parts with non-flat, non-uniform geometry, honeycombs must be machined or thermoformed with great care and expense. The ability to produce shaped honeycombs would allow sandwich panels to replace monolithic parts in a number of high performance, space-constrained applications, while also providing new areas of research for structural optimization, distributed sensing and actuation, and on-site production of infrastructure. Previous work has shown methods of directly producing shaped honeycombs by cutting and folding flat sheets of material. This research extends these methods by demonstrating work towards a continuous process for the cutting and folding steps of this process. An algorithm for producing a manufacturable cut-and-fold pattern from a three-dimensional volume is designed, and a machine for automatically performing the required cutting and parallel folding is proposed and prototyped. The accuracy of the creases placed by this machine is characterized and the impact of creasing order is demonstrated. Finally, a prototype part is produced and future work is sketched towards full process automation.

scholarly journals Small Oligonucleotides Detection in Three-Dimensional Polymer Network of DNA-PEG Hydrogels

2021 ◽  
Author(s):  
Alessia Mazzarotta ◽  
Tania Maristella Caputo ◽  
Luca Raiola ◽  
Edmondo Battista ◽  
Paolo Antonio Netti ◽  
...  
Keyword(s):  
Polymer Network ◽  
Three Dimensional ◽  
Mesh Size ◽  
Short Oligonucleotide ◽  
Dna Oligonucleotides ◽  
Hydrogel Network ◽  
Displacement Assay ◽  
Oligonucleotide Detection ◽  
Biomolecules Detection ◽  
And Diffusion

The control of the three-dimensional (3D) polymer network structure is important for permselective materials when specific biomolecules detection is needed. Here we investigate conditions to obtain a tailored hydrogel network that combine both molecular filtering and molecular capture capabilities for biosensing applications. Along this line short oligonucleotide detection in a displacement assay is set within PEGDA hydrogels synthetized by UV radical photopolymerization. To provide insights on the molecular filter capability, diffusion studies of several probes (sulforhodamine G and dextrans) with different hydrodynamic radii were carried out using NMR technique. Moreover, fluorometric analyses of hybridization of DNA oligonucleotides inside PEGDA-hydrogels shed light on the mechanisms of recognition in 3D, highlighting that mesh size and crowding effect greatly impact of hybridization mechanism onto polymer network. Finally, we found the best probe density and diffusion transport conditions to allow the specific oligonucleotide capture and detection inside PEGDA-hydrogels for oligonucleotide detection and the filtering out of higher molecular weight molecules.

scholarly journals Porous Geometry Guided Micro-mechanical Environment Within Scaffolds for Cell Mechanobiology Study in Bone Tissue Engineering

2021 ◽  
Vol 9 ◽  
Author(s):  
Feihu Zhao ◽  
Yi Xiong ◽  
Keita Ito ◽  
Bert van Rietbergen ◽  
Sandra Hofmann
Keyword(s):  
Porous Scaffold ◽  
Mechanical Strain ◽  
Three Dimensional ◽  
Pore Geometry ◽  
Cell Physiology ◽  
Porous Scaffolds ◽  
Mechanical Environment ◽  
Functional Features ◽  
Future Work

Mechanobiology research is for understanding the role of mechanics in cell physiology and pathology. It will have implications for studying bone physiology and pathology and to guide the strategy for regenerating both the structural and functional features of bone. Mechanobiological studies in vitro apply a dynamic micro-mechanical environment to cells via bioreactors. Porous scaffolds are commonly used for housing the cells in a three-dimensional (3D) culturing environment. Such scaffolds usually have different pore geometries (e.g. with different pore shapes, pore dimensions and porosities). These pore geometries can affect the internal micro-mechanical environment that the cells experience when loaded in the bioreactor. Therefore, to adjust the applied micro-mechanical environment on cells, researchers can tune either the applied load and/or the design of the scaffold pore geometries. This review will provide information on how the micro-mechanical environment (e.g. fluid-induced wall shear stress and mechanical strain) is affected by various scaffold pore geometries within different bioreactors. It shall allow researchers to estimate/quantify the micro-mechanical environment according to the already known pore geometry information, or to find a suitable pore geometry according to the desirable micro-mechanical environment to be applied. Finally, as future work, artificial intelligent – assisted techniques, which can achieve an automatic design of solid porous scaffold geometry for tuning/optimising the micro-mechanical environment are suggested.

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