Simulation studies of permeation through two-dimensional ideal polymer networks

We study the diffusion process through an ideal polymer network, using numerical methods. Polymers are modeled by random walks on the bonds of a two-dimensional square lattice. Molecules occupy the lattice cells and may jump to the nearest-neighbor cells, with probability determined by the occupation of the bond separating the two cells. Subjected to a concentration gradient across the system, a constant average current flows in the steady state. Its behavior appears to be a non-trivial function of polymer length, mass density and temperature, for which we offer qualitative explanations.Comment: 8 pages, 4 figure

Gas permeation through a polymer network

We study the diffusion of gas molecules through a two-dimensional network of polymers with the help of Monte Carlo simulations. The polymers are modeled as non-interacting random walks on the bonds of a two-dimensional square lattice, while the gas particles occupy the lattice cells. When a particle attempts to jump to a nearest-neighbor empty cell, it has to overcome an energy barrier which is determined by the number of polymer segments on the bond separating the two cells. We investigate the gas current $J$ as a function of the mean segment density $\rho$, the polymer length $\ell$ and the probability $q^{m}$ for hopping across $m$ segments. Whereas $J$ decreases monotonically with $\rho$ for fixed $\ell$, its behavior for fixed $\rho$ and increasing $\ell$ depends strongly on $q$. For small, non-zero $q$, $J$ appears to increase slowly with $\ell$. In contrast, for $q=0$, it is dominated by the underlying percolation problem and can be non-monotonic. We provide heuristic arguments to put these interesting phenomena into context.Comment: Dedicated to Lothar Schaefer on the occasion of his 60th birthday. 11 pages, 3 figure

Autonomous detection and anticipation of jam fronts from messages propagated by inter-vehicle communication

In this paper, a minimalist, completely distributed freeway traffic information system is introduced. It involves an autonomous, vehicle-based jam front detection, the information transmission via inter-vehicle communication, and the forecast of the spatial position of jam fronts by reconstructing the spatiotemporal traffic situation based on the transmitted information. The whole system is simulated with an integrated traffic simulator, that is based on a realistic microscopic traffic model for longitudinal movements and lane changes. The function of its communication module has been explicitly validated by comparing the simulation results with analytical calculations. By means of simulations, we show that the algorithms for a congestion-front recognition, message transmission, and processing predict reliably the existence and position of jam fronts for vehicle equipment rates as low as 3%. A reliable mode of operation already for small market penetrations is crucial for the successful introduction of inter-vehicle communication. The short-term prediction of jam fronts is not only useful for the driver, but is essential for enhancing road safety and road capacity by intelligent adaptive cruise control systems.Comment: Published in the Proceedings of the Annual Meeting of the Transportation Research Board 200

A new multi-anticipative car-following model with consideration of the desired following distance

We propose in this paper an extension of the multi-anticipative optimal velocity car-following model to consider explicitly the desired following distance. The model on the following vehicle’s acceleration is formulated as a linear function of the optimal velocity and the desired distance, with reaction-time delay in elements. The linear stability condition of the model is derived. The results demonstrate that the stability of traffic flow is improved by introducing the desired following distance, increasing the time gap in the desired following distance or decreasing the reaction-time delay. The simulation results show that by taking into account the desired following distance as well as the optimal velocity, the multi-anticipative model allows longer reaction-time delay in achieving stable traffic flows

Scenario-Based Design Theorizing:The Case of a Digital Idea Screening Cockpit

As ever more companies encourage employees to innovate, a surplus of ideas has become reality in many organizations – often exceeding the available resources to execute them. Building on insights from a literature review and a 3-year collaboration with a banking software provider, the paper suggests a Digital Idea Screening Cockpit (DISC) to address this challenge. Following a design science research approach, it suggests a prescriptive design theory that provides practitioner-oriented guidance for implementing a DISC. The study shows that, in order to facilitate the assessment, selection, and tracking of ideas for different stakeholders, such a system needs to play a dual role: It needs to structure decision criteria and at the same be flexible to allow for creative expression. Moreover, the paper makes a case for scenario-based design theorizing by developing design knowledge via scenarios

Discourse Quality in Times of Populism: An Analysis of German Parliamentary Debates on Immigration Policy

Right-wing populists are on the rise in Europe in the last decade. Their populism undermines one of the central pillars of democracy, the political discourse. Populism affects the quality of political debates in parliaments. With the emergence of the “Alternative für Deutschland” (AfD) a populist party became relevant nationally for the first time in over sixty years. By applying the concept of Cognitive Complexity as an instrument to measure deliberative quality, we analyze to what extend the discourse quality in the German Bundestag in debates on immigration policies varied over the 18th legislative period. Cognitive Complexity is measured quantitatively by applying a linguistic approach based on the LIWC dictionary. Despite our initial expectations, there are no trends detectable and the rise of the populist AfD does not alter the discourse quality so far. Nonetheless, there exist major differences in discourse quality between the parties, most notably opposition parties have a lower discourse quality in their statements than governing parties. In addition, individual characteristics of the speaker such as gender, age or electoral type do not render any differences. However, there seem to be differences depending on the federal state in which the speaker’s electoral district lies

Regionalized management in solid waste public policy in Brazil and its consequences

A política brasileira de resíduos sólidos no país ainda carece de muita efetivação legal, motivo pelo qual o estado do Paraná, nas regiões de Paranavaí e Maringá foi alvo, em 2019, da “Operação Percola” do Ministério Público do Paraná. A conclusão da operação mostrou que os municípios possuem dificuldade, principalmente orçamentária, na implementação das determinações legais. Dessa forma, o objetivo do artigo é verificar o reflexo da gestão na região para cumprimento da lei. Os dados empregados são secundários e foram coletados por meio do Sistema Nacional de Informação de Saneamento – Resíduos Sólidos (SNIS) e conteúdo dos procedimentos do Ministerio Público do Parana (MPPR). Constata-se que os municípios que buscaram adotar a gestão regionalizada, tiveram melhores avanços, no que tange ao crescimento de suporte, elaboração e aprovação de planos municipais. De outro lado, a instituição de cobrança ou adesão ao programa “Eu pago pelo meu lixo” não teve muito impacto.The brasilian solid waste policy in the country still lacks many implementations, which is why the state of Paraná, more specifically the regions of Paranavaí and Maringá, were involved in the "Operation Percola". The conclusion of the operation showed that the main problem of the cities is financial resources. Thus, the objective of the article is to verify the reflection of the management in the region for compliance with the law. The data used are secondary and were collected through the National Sanitation Information System – Solid Waste (SNIS) and by conclusions developed by the Public Defenders of Parana (MPPR). Among the results presented, it can be seen that the municipalities that sought to adopt regionalized or consortium management had better progress in terms of receiving support, preparing and approving municipal plans. On the other hand, it is possible to see that the billing institution or adhesion to the “I pay for my garbage” program did not have much impact.info:eu-repo/semantics/publishedVersio

Consistent Value of Two-Stage Pedicle Flaps in the Age of Microsurgical Maxillofacial Reconstruction

Introduction Up to the second half of the twentieth century, pedicled flaps marked the gold standard in reconstructive surgery. Followed by the introduction of microsurgical techniques, these flaps were increasingly abandoned. We conducted a retrospective study to determine the value of two-stage pedicle flaps in modern maxillofacial reconstruction. Material & Methods A chart review from October 2017 to November 2020 was performed to identify patients who were treated by a two-stage pedicle flap in our Department of Oral and Maxillofacial Surgery. Results A total of 31 patients, 17 female and 14 males received 36 two-stage pedicle flaps. All patients were in noticeably impaired health condition with a majority of ASA-score 3. The defect location mainly contained extraoral resections (58.3%). A variety of flaps were harvested consisting of buccal flaps, Abbe flaps, forehead flaps, deltopectoral flaps, nasolabial flaps, and a tubed flap. Discussion The study outlines two indications for the use of two-stage pedicle flaps. Firstly, as a back-up strategy in heavily pre-treated wound beds and secondly in an almost contrarily indication as a first-choice reconstructive option of the facial skin in esthetic demanding cases. Conclusion The timesaving and straight forward surgical approach as well as their low postsurgical complications and strong long-time success rates secure the two-stage pedicle flap a justified niche role in times of microsurgical maxillofacial reconstruction