Pattern Selection and Super-patterns in the Bounded Confidence Model

We study pattern formation in the bounded confidence model of opinion dynamics. In this random process, opinion is quantified by a single variable. Two agents may interact and reach a fair compromise, but only if their difference of opinion falls below a fixed threshold. Starting from a uniform distribution of opinions with compact support, a traveling wave forms and it propagates from the domain boundary into the unstable uniform state. Consequently, the system reaches a steady state with isolated clusters that are separated by distance larger than the interaction range. These clusters form a quasi-periodic pattern where the sizes of the clusters and the separations between them are nearly constant. We obtain analytically the average separation between clusters L. Interestingly, there are also very small quasi-periodic modulations in the size of the clusters. The spatial periods of these modulations are a series of integers that follow from the continued fraction representation of the irrational average separation L.Comment: 6 pages, 6 figure

Effects of sulfonation process on thermal behavior and microstructure of sulfonated polysulfone membranes as a material for Proton Exchange Membrane (PEM)

This paper reports the effect of sulfonation processon thermal behavior and microstrucutre of sulfonated polysulfone membrane. Various degree of sulfonation reactin has been conducted and the sulfonated membranes were characterized by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), x-ray diffraction (XRD) and scanning electron microscopy (SEM). Modifications of the origin polysulfone polymer resulted in an increment value of glass transition temperature (Tg) due to the introduction of sulfonic acid group to the polymer backbone. However, due to some hindrance such as trace amount of organic solvent left during solvent evaporation and high hydrophilicity of the produced sulfonated membranes resulted in decreasing values of Tg. The polymer membrane showed lower degradation temperature as a function of degree of sulfonation. From XRD analysis, it was found that the membrane shows slight crystalline behavior after the sulfonation reaction. Detail discussions and observation of the alteration in microstructure of the sulfonated membrane were supported by SEM micrograph

Effect of non-solvent additives on the structure and performance of PVDF hollow fiber membrane contactor for CO2 stripping

Microporous polyvinylidene fluoride (PVDF) hollow fiber membranes with various non-solvent additives, i.e. lithium chloride, glycerol, polyethylene glycol (PEG-400), methanol and phosphoric acid, were fabricated for CO2 stripping via membrane contactors. The membranes were characterized in terms of liquid entry pressure, contact angle, gas permeation and morphology analysis. CO2 stripping performance was investigated by using an in-house made stainless steel module with CO2-preloaded aqueous diethanolamine as the liquid absorbent. Hydrophobicity and gas permeability of the membranes reduced with the addition of a non-solvent additive in the polymer dope but increase in liquid entry pressure was observed as more sponge-like structures developed in the inner layer of the fibers. It was found that PVDF/PEG-400 membrane produced the highest stripping flux of 4.03×10-2 mol m-2 s-1 which can be correlated to its high gas permeation and high effective surface porosity. The result of long-term stripping operation indicated an approximatly 80% stripping flux reduction which can be related to the interaction of polymer membrane and amine solution at high temperature

Detectability of High Redshift Ellipticals in the Hubble Deep Field

Relatively few intensively star-forming galaxies at redshifts z>2.5 have been found in the Hubble Deep Field (HDF). This has been interpreted to imply a low space density of elliptical galaxies at high z, possibly due to a late (z<2.5) epoch of formation, or to dust obscuration of the ellipticals that are forming at z~3. I use HST UV (2300 Ang) images of 25 local early-type galaxies to investigate a third option, that ellipticals formed at z>4.5, and were fading passively by 2<z<4.5. Present-day early-types are faint and centrally concentrated in the UV. If ellipticals formed their stars in a short burst at z>4.5, and have faded passively to their present brightnesses at UV wavelengths, they would generally be below the HDF detection limits in any of its bands at z>2.5. Quiescent z ~ 3 ellipticals, if they exist, should turn up in sufficiently deep IR images.Comment: AAS LaTex, 11 pages, 1 table, 1 figure, some corrections and clarifications, accepted for publication in ApJ

Approaches to Automated Morphological Classification of Galaxies

There is an obvious need for automated classification of galaxies, as the number of observed galaxies increases very fast. We examine several approaches to this problem, utilising {\em Artificial Neural Networks} (ANNs). We quote results from a recent study which show that ANNs can classsify galaxies morphologically as well as humans can.Comment: 8 pages, uu-encoded compressed postscript file (containing 2 figures

Dynamics of Three Agent Games

We study the dynamics and resulting score distribution of three-agent games where after each competition a single agent wins and scores a point. A single competition is described by a triplet of numbers $p$, $t$ and $q$ denoting the probabilities that the team with the highest, middle or lowest accumulated score wins. We study the full family of solutions in the regime, where the number of agents and competitions is large, which can be regarded as a hydrodynamic limit. Depending on the parameter values $(p,q,t)$, we find six qualitatively different asymptotic score distributions and we also provide a qualitative understanding of these results. We checked our analytical results against numerical simulations of the microscopic model and find these to be in excellent agreement. The three agent game can be regarded as a social model where a player can be favored or disfavored for advancement, based on his/her accumulated score. It is also possible to decide the outcome of a three agent game through a mini tournament of two-a gent competitions among the participating players and it turns out that the resulting possible score distributions are a subset of those obtained for the general three agent-games. We discuss how one can add a steady and democratic decline rate to the model and present a simple geometric construction that allows one to write down the corresponding score evolution equations for $n$-agent games

Exploring The Role Of Cyber Security Measures (Encryption, Firewalls, And Authentication Protocols) In Preventing Cyber-Attacks On E-Commerce Platforms

The present study seeks to examine the significance of cybersecurity measures, specifically encryption strength (ES), firewall configuration (FC), and authentication protocols (AP), in protecting e-commerce platforms against cyber-attacks. The data collection process involved the administration of a survey to IT professionals responsible for overseeing e-commerce operations in a range of organisations located in Saudi Arabia. A convenience sampling method was employed to distribute a total of 300 questionnaires, out of which 190 completed responses were selected for analysis. The measurement model, which encompassed variables such as ES, FC, AP, security training (ST), cyber-attack incidents (CAI), customer trust (CT), and incident response time (IRT), was estimated using the structural equation model in Amos. The results of this study provide insights into the relationship between cybersecurity measures and their influence on the frequency of cyberattacks. The study highlights the significance of encryption, firewall configuration, and authentication protocols in strengthening e- commerce platforms. Additionally, this study examines the impact of security training on the improvement of overall cybersecurity posture and its subsequent effect on customer trust. The examination also takes into account the duration of incident response as a critical element in minimising the consequences of cyber incidents. The findings obtained from this study contribute to a more comprehensive comprehension of the cybersecurity environment within the realm of electronic commerce