Lab-scale Reproduction of Siloxane Foam Synthesis

Evonik has a synthesis reaction to create siloxane-based foam for sale that they run in their Hopewell plant. They would like to utilize a bench scale reactor system for experimentation on the process. The problem is that the foam created on the lab scale does not show the same properties as the foam created on the plant scale and to run experiments accurately they would have to use the plant reactor, wasting both reactor time and plant resources. Evonik wanted the Senior Design team to find a way of recreating the conditions of the plant reactor on the lab scale so that experiments could be run in a way that eliminates waste and gives accurate data. The final direction of the project was to provide a 1 Liter jacketed glass reactor and an outline for a recirculation bath that would mimic the heating profile of the plant reactor as closely as possible, as well as a way to provide a comparable agitation profile to the plant scale. To facilitate the agitation profile, an equation was found to relate the size and speed of both the lab and plant impellers. In addition, a quantitative method of measuring “good” and “bad” quality of the product was discovered in UV-Vis Spectroscopy, which allows Evonik to instantly test the liquid product without having to “foam up” the product and test qualitatively.https://scholarscompass.vcu.edu/capstone/1157/thumbnail.jp

The configuration multi-edge model: Assessing the effect of fixing node strengths on weighted network magnitudes

Complex networks grow subject to structural constraints which affect their measurable properties. Assessing the effect that such constraints impose on their observables is thus a crucial aspect to be taken into account in their analysis. To this end,we examine the effect of fixing the strength sequence in multi-edge networks on several network observables such as degrees, disparity, average neighbor properties and weight distribution using an ensemble approach. We provide a general method to calculate any desired weighted network metric and we show that several features detected in real data could be explained solely by structural constraints. We thus justify the need of analytical null models to be used as basis to assess the relevance of features found in real data represented in weighted network form.Comment: 11 pages. 4 figure

Optimization as a result of the interplay between dynamics and structure

In this work we study the interplay between the dynamics of a model of diffusion governed by a mechanism of imitation and its underlying structure. The dynamics of the model can be quantified by a macroscopic observable which permits the characterization of an optimal regime. We show that dynamics and underlying network cannot be considered as separated ingredients in order to achieve an optimal behavior.Comment: 12 pages, 4 figures, to appear in Physica

大学说明性课程中参与式互动的规范。基于观察方法作为混合方法策略的共建训练建议

El objetivo de este artículo es compartir algunas consideraciones de fondo y procedimiento sobre la comunicación académica modelada por la interacción participativa en el marco de la formación co-constructiva del profesorado. A partir de un estudio de caso múltiple en aula universitaria se analiza el formato expositivo-magistral con actores motivados a sostener su posición dialógica de rol en la interacción comunicativa y facilitar los actos de ayuda recíproca, recursos discursivos e interactivos que cumplen una función estratégica porque son necesarios para la construcción intelectual y autónoma del aprendizaje. La investigación empírica se diseña como un estudio de observación sistemática con un propósito evaluativo y que implementa la integración de los análisis cualitativos y cuantitativos desde un enfoque mixed methods. La discusión de los resultados pone en valor la flexibilidad y la adecuación del método utilizado tanto en el plano de la descripción matizada del proceso de regulación de la interacción participativa intentada por los actores como en el plano de la evaluación formativa de los puntos fuertes y débiles observados.The objective of this article is to share some background and procedural considerations on academic communication modeled by participatory interaction in the co-constructive training framework for teachers. From a case study in a university classroom, the expository-lectures format is analyzed with actors motivated to sustain their dialogical position of role in communicative interaction and facilitate acts of reciprocal help as well as discursive and interactive resources that fulfill a strategic function because they are necessary for the intellectual and autonomous construction of learning. Empirical research is designed as a systematic observation study with an evaluative purpose and that implements the integration of qualitative and quantitative analysis from a «mixed methods» approach. The discussion of the results highlights the flexibility and suitability of the method used both in terms of the nuanced description of the participatory interaction process attempted by the actors and in terms of the formative assessment of the strengths and weaknesses of the expository-lectures observed.Цель данной статьи - поделиться некоторыми исходными данными и процедурными соображениями об академической коммуникации, моделируемой партисипативным взаимодействием в рамках ко-конструктивного обучения преподавателей. На примере университетской аудитории анализируется формат докладов-лекций с действующими лицами, мотивированными на поддержание своей диалогической роли в коммуникативном взаимодействии и содействие актам взаимной помощи, а также дискурсивные и интерактивные ресурсы, выполняющие стратегическую функцию, поскольку они необходимы для интеллектуального и автономного построения обучения. Эмпирическое исследование построено как систематическое наблюдательное исследование с оценочной целью, в котором реализована интеграция качественного и количественного анализа на основе подхода «смешанных методов». Обсуждение результатов подчеркивает гибкость и пригодность используемого метода как в плане детального описания процесса партисипативного взаимодействия, который пытались осуществить участники, так и в плане формативной оценки сильных и слабых сторон наблюдаемых докладов-лекций.本文的目的是在对教师的共建培训框架内分享以参与式互动为模型的学术交流的一些背景及其过程。我们从大学课堂的多个案例研究中分析了说明性-权威模式，其中参与者被鼓励坚持其在交流互动中的对话角色地位，并推动互惠帮助的行为和具有战略功能的话语和互动资源，因为它们是知识与自主学习建构所必需的。该实证研究被设计为具有评估目的的系统观察研究，从混合方法角度整合了定性和定量分析。对结果的讨论中从两方面强调了该方法的灵活性和充分性，一方面为对参与者尝试的参与式互动过程的细致描述方面，另一方面是在对所观察到的说明性讲座的优缺点的形成性评估方面

Synchronization in a ring of pulsating oscillators with bidirectional couplings

We study the dynamical behavior of an ensemble of oscillators interacting through short range bidirectional pulses. The geometry is 1D with periodic boundary conditions. Our interest is twofold. To explore the conditions required to reach fully synchronization and to invewstigate the time needed to get such state. We present both theoretical and numerical results.Comment: Revtex, 4 pages, 2 figures. To appear in Int. J. Bifurc. and Chao

Detection of Rotational Spectral Variation on the M-type asteroid (16) Psyche

The asteroid (16) Psyche is of scientific interest because it contains ~ 1% of the total mass of the asteroid belt and is thought to be the remnant metallic core of a protoplanet. Radar observations have indicated the significant presence of metal on the surface with a small percentage of silicates. Prior ground-based observations showed rotational variations in the near-infrared (NIR) spectra and radar albedo of this asteroid. However, no comprehensive study that combines multi-wavelength data has been conducted so far. Here we present rotationally resolved NIR spectra (0.7-2.5 microns) of (16) Psyche obtained with the NASA Infrared Telescope Facility. These data have been combined with shape models of the asteroid for each rotation phase. Spectral band parameters extracted from the NIR spectra show that the pyroxene band center varies from ~ 0.92 to 0.94 microns. Band center values were used to calculate the pyroxene chemistry of the asteroid, whose average value was found to be Fs30En65Wo5. Variations in the band depth were also observed, with values ranging from 1.0 to 1.5%. Using a new laboratory spectral calibration we estimated an average orthopyroxene content of 6+/-1%. The mass-deficit region of Psyche, which exhibits the highest radar albedo, also shows the highest value for spectral slope and the minimum band depth. The spectral characteristics of Psyche suggest that its parent body did not have the typical structure expected for a differentiated body or that the sequence of events that led to its current state was more complex than previously thought.Comment: 21 pages, 8 figures, 2 tables, published in The Astronomical Journa

Synchronization reveals topological scales in complex networks

We study the relationship between topological scales and dynamic time scales in complex networks. The analysis is based on the full dynamics towards synchronization of a system of coupled oscillators. In the synchronization process, modular structures corresponding to well defined communities of nodes emerge in different time scales, ordered in a hierarchical way. The analysis also provides a useful connection between synchronization dynamics, complex networks topology and spectral graph analysis.Comment: 4 pages, 3 figure