Molecular dynamics computer simulation of scratch resistance testing of polymers: visualization

Experimental scratch resistance testing provides two numbers: the penetration depth Rp and the healing depth Rh. In molecular dynamics computer simulations, we create a material consisting of N statistical chain segments by polymerization; a reinforcing phase can be included. Then we simulate the movement of an indenter and response of the segments during X time steps. Each segment at each time step has three Cartesian coordinates of position and three of momentum. We describe methods of visualization of results based on a record of 6NX coordinates. We obtain a continuous dependence on time t of positions of each of the segments on the path of the indenter. Scratch resistance at a given location can be connected to spatial structures of individual polymeric chains.

Polymer indentation with mesoscopic molecular dynamics

Indentation tests are used to determine the hardness of a material, e.g., Rockwell, Vickers, or Knoop. The indentation process is empirically observed in the laboratory during these tests; the mechanics of indentation is insufficiently understood. We have performed first molecular dynamics computer simulations of indentation resistance of polymers with a chain structure similar to that of high density polyethylene (HDPE). A coarse grain model of HDPE is used to simulate how the interconnected segments respond to an external force imposed by an indenter. Results include the time-dependent measurement of penetration depth, recovery depth, and recovery percentage, with respect to indenter force, indenter size, and indentation time parameters. The simulations provide results that are inaccessible experimentally, including continuous evolution of the pertinent tribological parameters during the entire indentation process.

Simulating scratch behavior of polymers with mesoscopic molecular dynamics

Part replacement and repair is needed in structures with moving parts because of scratchability and wear. In spite of some accumulation of experimental evidence, scratch resistance is still not well understood. We have applied molecular dynamics to study scratch resistance of amorphous polymeric materials through computer simulations. As a first approach, a coarse grain model was created for high density polyethylene at the mesoscale. We have also extended the traditional approach and used real units rather than reduced units (to our knowledge, for the first time), which enable an improved quantification of simulation results. The obtained results include analysis of penetration depth, residual depth and recovery percentage related to indenter force and size. Our results show there is a clear effect from these parameters on the tribological properties. We also discuss a "crooked smile" effect on the scratched surface and the reasons for its appearance.

Pectus Excavatum postsurgical outcome based on preoperative soft body dynamics simulation

Pectus excavatum is the most common congenital deformity of the anterior chest wall, in which an abnormal formation of the rib cage gives the chest a caved-in or sunken appearance. Today, the surgical correction of this deformity is carried out in children and adults through Nuss technic, which consists in the placement of a prosthetic bar under the sternum and over the ribs. Although this technique has been shown to be safe and reliable, not all patients have achieved adequate cosmetic outcome. This often leads to psychological problems and social stress, before and after the surgical correction. This paper targets this particular problem by presenting a method to predict the patient surgical outcome based on pre-surgical imagiologic information and chest skin dynamic modulation. The proposed approach uses the patient pre-surgical thoracic CT scan and anatomical-surgical references to perform a 3D segmentation of the left ribs, right ribs, sternum and skin. The technique encompasses three steps: a) approximation of the cartilages, between the ribs and the sternum, trough b-spline interpolation; b) a volumetric mass spring model that connects two layers - inner skin layer based on the outer pleura contour and the outer surface skin; and c) displacement of the sternum according to the prosthetic bar position. A dynamic model of the skin around the chest wall region was generated, capable of simulating the effect of the movement of the prosthetic bar along the sternum. The results were compared and validated with patient postsurgical skin surface acquired with Polhemus FastSCAN system

Bananas, Dark Worlds, and AspectH: (Group 5 Discussion)

This report summarises our idea of code clone detection in Haskell code and refactorings based on identified clones as it evolved in our group-of-three discussion

Direct communication versus virtual communication in virtual teams

Several studies suggest that computer-mediated communication can lead to decreases in group effectiveness and reduce satisfaction levels in terms of trust and comfort of its users. Supported by an experiment, where the emotional or affective aspects of communication were tested with the experimentation of two architectures, Direct Communication Architecture (DCA) and the Virtual Communication Architecture (VCA) this paper validates the thesis that, from the users’ perspective, there is no opposition to the acceptance of virtual environments and interfaces for communication, and that these environments are able to cope with the reconfiguration dynamics requirements of virtual teams or client-server relations in a virtual enterprise operation.

Network dynamics in scientific knowledge acquisition: an analysis in three public universities in the state of Bahia

This paper aims to cast some light on the dynamics of knowledge networks in developing countries by analyzing the scientific production of the largest university in the Northeast of Brazil and its influence on some of the remaining regional research institutions in the state of Bahia. Using a methodology test to be employed in a larger project, the Universidade Federal da Bahia (UFBA) (Federal University of Bahia), the Universidade do Estado da Bahia (Uneb) (State of Bahia University) and the Universidade Estadual de Santa Cruz (Uesc)'s (Santa Cruz State University) scientific productions are discussed in one of their most traditionally expressive sectors in academic production - namely, the field of chemistry, using social network analysis of co-authorship networks to investigate the existence of small world phenomena and the importance of these phenomena in research performance in these three universities. The results already obtained through this research bring to light data of considerable interest concerning the scientific production in unconsolidated research universities. It shows the important participation of the UFBA network in the composition of the other two public universities research networks, indicating a possible occurrence of small world phenomena in the UFBA and Uesc networks, as well as the importance of individual researchers in consolidating research networks in peripheral universities. The article also hints that the methodology employed appears to be adequate insofar as scientific production may be used as a proxy for scientific knowledge.

A System Dynamics-Based Simulation Experiment for Testing Mental Model and Performance Effects of Using the Balanced Scorecard

This study develops a theoretical model that explains the effectiveness of the balanced scorecard approach by means of a system dynamics and feedback learning perspective. Presumably, the balanced scorecard leads to a better understanding of context, allowing managers to externalize and improve their mental models. We present a set of hypotheses about the influence of the balanced scorecard approach on mental models and performance. A test based on a simulation experiment that uses a system dynamics model is performed. The experiment included three types of parameters: financial indicators; balanced scorecard indicators; and balanced scorecard indicators with the aid of a strategy map review. Two out of the three hypotheses were confirmed. It was concluded that a strategy map review positively influences mental model similarity, and mental model similarity positively influences performance.

A system dynamics-based simulation

This study develops a theoretical model that explains the effectiveness of the balanced scorecard approach by means of a system dynamics and feedback learning perspective. Presumably, the balanced scorecard leads to a better understanding of context, allowing managers to externalize and improve their mental models. We present a set of hypotheses about the influence of the balanced scorecard approach on mental models and performance. A test based on a simulation experiment that uses a system dynamics model is performed. The experiment included three types of parameters: financial indicators; balanced scorecard indicators; and balanced scorecard indicators with the aid of a strategy map review. Two out of the three hypotheses were confirmed. It was concluded that a strategy map review positively influences mental model similarity, and mental model similarity positively influences performance.

Strategy Lab Experiences: Bathtub Dynamics

As the world changes ever faster, managers increasingly recognize the complexity and turbulence of the business systems in which they are embedded. The management problems are dynamic, while the dynamic complexity comes frequently from few variables with circle and delays interrelations that introduce nonlinearities.The present paper describes a research conducted in Portugal with two different groups - one, academic; the other, professional - where we explored the subjects’ understanding of some basic systems thinking concepts such as stock-flow relationship, feedback processes and time delays.

Aprender com os outros : uma estratégia para a inclusão de um aluno com Autismo

Este Projecto de Intervenção, “Aprender com os outros - uma estratégia para a inclusão de um aluno com autismo”, fundamentado nos pressupostos e nos procedimentos da investigação-acção, centrou-se nas acções em áreas de maior e menor sucesso do aluno, de nome fictício “Francisco”, no âmbito da língua portuguesa e da socialização, numa perspectiva inclusiva. Este aluno considerado com necessidades educativas especiais (NEE) apresentava perturbações do espectro do autismo (PEA), o que, à partida, se repercutia no seu défice de atenção, na autonomia para a realização das tarefas escolares, na área da linguagem e da comunicação e na interacção social. Como as interacções na turma e com a turma são essenciais para a aprendizagem, propusemo-nos implementar actividades específicas para o desenvolvimento das competências sociais e cognitivas, com abordagem comportamentalista, numa turma do 3º ano de escolaridade, onde estava incluído um aluno diagnosticado com PEA. Também procurámos desenvolver as suas competências académicas, através do trabalho realizado no grupo e com o grupo-turma, criando as condições que favorecessem a socialização do aluno e a sua autonomia. Para atingirmos aqueles objectivos, iniciámos um trabalho a pares e depois em pequenos grupos, para desta forma incluir o “Francisco” na dinâmica das aulas, para que participasse nas actividades propostas, obtendo o respeito dos colegas na valorização das suas intervenções e do seu ritmo de trabalho. Os objectivos definidos, bem como as actividades realizadas e avaliadas, implicando todos os intervenientes no processo, permitiram que o “Francisco” fizesse aprendizagens significativas nas áreas, académica, social, da autonomia e da comunicação. Segundo Silva (2009), a inclusão dos alunos considerados com necessidades educativas especiais no ensino regular implica mudanças ao nível das atitudes e das práticas pedagógicas de todos os intervenientes no processo ensino e aprendizagem, da organização e da gestão na sala de aula e na própria escola enquanto instituição. Acreditamos que só desta forma se pode proporcionar aos alunos marcados pela diferença, que é um valor em si mesma (Rodrigues, 2006; Leitão, 2006; Sanches & Teodoro, 2006; Silva, 2009), as mesmas experiências, aprendizagens e vivências que são proporcionadas aos restantes colegas.

Property and age organisation among an East African pastoralist group

Estudos sobre sistemas etários na África Oriental têm focado principalmente as regras que regulam recrutamento, com ênfase ao modo em que se mantém a autoridade e os cargos políticos, assim como à natureza não-militar e não-política dos sistemas etários. Apesar de contribuírem enormemente para a nossa compreensão das organizações etárias na região, esses estudos não lidam explicitamente com a questão da propriedade e com o modo em que ela constitui um dos principais focos para atividades de organizações etárias. De fato, quando se menciona a propriedade, ela é vista em função das famílias e, portanto, do parentesco. Apresentando e discutindo uma variedade de casos envolvendo o modo em que a propriedade é tratada por lideranças de um conjunto etário/geracional e residentes Hor e não-Hor do território Hor, este estudo conclui que a posse, o uso e controle de recursos não constitui um assunto que pertence exclusivamente à esfera de grupos de parentesco; trata-se também de uma questão central para organizações etárias. Apesar de haver, aparentemente, alguma ambigüidade decorrente da ênfase equilibrada que os Hor dedicam ao parentesco e às categorias etárias e suas complementaridades em assuntos relacionados à economia, à religião e ao direito, dados referentes aos Hor revelam uma tendência a tratar questões referentes ao uso de recursos cruciais em termos de organização etária. Trata-se de um estudo sobre os Hor (Arbore), um povo pastoril do Sudoeste da Etiópia.

Health knowledge of prostitutes in Saigon, Vietnam: a study of health attitudes and habits relating to venereal diseases taken from a group of prostitutes

A study of health knowledge and practices of prostitutes is presented here. The study took place at the V. D. Center in Saigon, Vietnam. It was designed with the objective of obtaining information to be used in preparing an educational program to be offered to the prostitutes at the Center, and for using, in preparing educational materials with focus on V. D. prevention. The outline of a course is also presented.

Kuailous ou Po tau ya : imagens no feminino sobre os portugueses em Macau

Tendo Macau por contexto, quinze anos após a transferência da sua administração para a República Popular da China e cinco séculos de presença portuguesa, o estudo efetua uma abordagem às representações e estereótipos sociais dos portugueses, a partir de um inquérito a cento e setenta e cinco mulheres chinesas desta Região Administrativa Especial (RAEM). Tendo como marcos conceptuais a Teoria das Representações Sociais, de Moscovici, e a Teoria da Identidade Social, de Tajfel, o estudo procura explicitar os saberes sociais construídos por esse grupo de referência, determinantes na forma como se processa a comunicação e a interação grupal com portugueses e âncora para a construção de estereótipos com os quais esses processos são simplificados, mas também enviesados. Antevendo-se, num horizonte não muito longínquo, decisões quanto à manutenção do princípio “um país, dois sistemas”, que viabiliza a preservação de marcas portuguesas (como a língua) e uma abertura especial à presença de portugueses em Macau, a compreensão das imagens e metáforas sobre esta comunidade constitui estratégia relevante para a perspetivação, no presente como no futuro, das relações intergrupais que a envolvem. O estudo conclui que as representações sobre os portugueses são, no essencial, de pendor positivo e exibem uma abertura à proximidade social e à participação desta comunidade nas dinâmicas sociais da RAEM. Mas assinala também áreas de potencial maior conflitualidade na defesa, pelo endogrupo, de áreas vitais de afirmação dessa nova ordem social pós- transferência.

An approach to absorptive capacity based on the Portuguese textile industry

The main purpose of this research is to identify the hidden knowledge and learning mechanisms in the organization in order to disclosure the tacit knowledge and transform it into explicit knowledge. Most firms usually tend to duplicate their efforts acquiring extra knowledge and new learning skills while forgetting to exploit the existing ones thus wasting one life time resources that could be applied to increase added value within the firm overall competitive advantage. This unique value in the shape of creation, acquisition, transformation and application of learning and knowledge is not disseminated throughout the individual, group and, ultimately, the company itself. This work is based on three variables that explain the behaviour of learning as the process of construction and acquisition of knowledge, namely internal social capital, technology and external social capital, which include the main attributes of learning and knowledge that help us to capture the essence of this symbiosis. Absorptive Capacity provides the right tool to explore this uncertainty within the firm it is possible to achieve the perfect match between learning skills and knowledge needed to support the overall strategy of the firm. This study has taken in to account a sample of the Portuguese textile industry and it is based on a multisectorial analysis that makes it possible a crossfunctional analysis to check on the validity of results in order to better understand and capture the dynamics of organizational behavior.