Este trabalho estuda a interação entre os métodos anti-ilhamento aplicados em sistemas fotovoltaicos residenciais, operando simultaneamente em uma rede de distribuição de baixa tensão. Os sistemas fotovoltaicos em geral interagem entre si, com a rede de distribuição da concessionária e com outras fontes de geração distribuída. Uma consequência importante dessa interação é a ocorrência do ilhamento, que acontece quando as fontes de geração distribuída fornecem energia ao sistema elétrico de potência mesmo quando esta se encontra eletricamente isolada do sistema elétrico principal. A função anti-ilhamento é uma proteção extremamente importante, devendo estar presente em todos os sistemas de geração distribuída. Atualmente, são encontradas diversas técnicas na literatura. Muitas delas oferecem proteção adequada quando um inversor está conectado à linha de distribuição, mas podem falhar quando dois ou mais funcionam simultaneamente, conectados juntos ou próximos entre si. Dois destes métodos são analisados detalhadamente nesse estudo, avaliados em uma rede de distribuição residencial de baixa tensão. Os resultados obtidos mostram que a influência de um método sobre o outro é dependente da predominância de cada um deles dentro do sistema elétrico. Contudo, nas condições analisadas o ilhamento foi detectado dentro do limite máximo estabelecido pelas normas pertinentes. / This work studies the interaction between islanding detection methods applied in residential photovoltaic systems, operating simultaneously in a low voltage distribution network. Photovoltaic systems, in general, interact with themselves, with the utility grid and other distributed generation sources. An important consequence of this interaction is the islanding occurrence, which happens when distributed generation sources supply energy to the electrical power system even when it is electrically isolated from the main electrical system. The anti-islanding function is an extremely important protection, and should be present in all distributed generation systems. Actually, many techniques are found in the literature. Most of them provide suitable protection when one inverter is connected to the distribution line, but can fail when two or more work simultaneously, connected at the same point or close to each other. Two of these methods are analyzed in detail in this study and evaluated in a residential low voltage distribution line. The obtained results show that the influence of a method over another one is dependent of the predominance of each one within the electrical system. However, in the analyzed condition the islanding was detected within the maximum allowed time established by applicable rules.

Este trabalho descreve um dormente monobloco de concreto protendido, o qual foi projetado para atender as características de uma via ferroviária brasileira. O dormente apresentou comportamento e resistência semelhantes aos dormentes de concreto comumente fabricados em vários países. A fim de verificar e aprovar o projeto, o dormente foi submetido a ensaios estáticos e dinâmicos, segundo as especificações da norma americana AREMA. Verificado e aprovado o projeto, dezoito dormentes foram fabricados sem e com fibras de aço, no teor de 60 kg/'M POT.3' (aproximadamente 0,75 % por volume). Ensaios estáticos e dinâmicos foram realizados em dormentes com e sem fibras de aço, com o objetivo de quantificar o benefício das fibras de aço à resistência estrutural do dormente. As fibras aumentaram o momento fletor de primeira fissura e o momento último, aumentaram significativamente a força de início de escorregamento dos fios de protensão e reduziram o espaçamento e a abertura das fissuras. As fibras também acrescentaram grande ductilidade aos dormentes e diminuíram a tensão nos fios de protensão, nos estágios mais avançados do carregamento. Sob ação dinâmica, as fibras reduziram a tensão nos fios de protensão mais tracionados em aproximadamente 100%, o que elevou significativamente a resistência do dormente à fadiga. Dormentes fabricados com menor força de protensão apresentaram excelente comportamento plástico e grande ductilidade, especialmente o dormente com fibras / This work describes a prestressed concrete monoblock railway sleeper designed according to a brazilian railway track. The sleeper was tested according to the Arema specifications in order to verify the project. The sleeper presented a structural behavior similar to the concrete railway sleepers used worldwide. After the preliminary tests, eighteen sleepers were manufactured without and with steel fibers contents of 60 Kg/'M POT.3' (about 0.75% by volume) and they were tested under static and dynamic loading to evaluate the fiber contribution on the resistance. Steel fibers increased the first crack and ultimate bending moments, reduced the deflection under ultimate load and increased significantly the slip force of the prestressing tendons. Reinforcing the sleeper with fibers also reduced the crack width and the spacing between cracks, adding higher ductility to the sleepers and decreasing the stress in the prestressing tendons under higher loads. The fibers increased significantly the fatigue strength under cyclic loading, decreasing the stress in the prestressing tendons in about 100%. The test results showed that sleepers manufactured with lower prestressed force have higher toughness, especially those reinforced with steel fibers

本研究的目的主要在於探討消費者在初進入陌生環境，不具備決策所需的相關資訊時，口耳相傳資訊的搜尋行為在消費者決策的過程中所扮演的角色，以及口耳相傳資訊在最終決策時發揮有效性的影響因素。 本研究以選課決策、參加社團選擇決策、學校附近飲料購買地點選擇決策等消費者會展現出不同涉入程度的三類決策為實驗標的，並以較不具備環境知識的大學新鮮人為受測對象，以實驗方法來探討涉入程度不同的決策類型與口耳相傳資訊搜尋行為、社會關係強度之關聯。 由實證結果可知，消費者在進行涉入程度較高的決策類型時，對於口耳相傳資訊的搜尋將愈趨積極，並愈傾向於向與本身具有較強社會關係的口耳相傳資訊提供者探詢意見。此外，當消費者對於口耳相傳資訊的搜尋愈趨主動時，也會愈傾向於向與本身具有較強社會關係的口耳相傳資訊提供者探詢意見，且由口耳相傳資訊搜尋活動中所獲致的助益也愈高。 在消費者個人的特質方面，本研究引入消費者國籍此一變數，受限於樣本的數目，本研究對於國籍議題所作成的初步結論為：來自不同國家的消費者，當其面對涉入程度不同的決策類型時，其對口耳相傳資訊的搜尋數量是有所差異的。

Granovetter proposed that weak ties connect different sections of social networks, thus function as the channel for individuals to gain access to useful information unavailable at existing social circles. The first motivation of this study is to explore to what extent strength of ties theory explains information exchange behaviour of Taiwanese Facebook users. According to past research, Chinese rely on those with close guanxi, such as family members and close friends to satisfy individual’s needs. This leads us to ask if guanxi would also play an important role in satisfying individual’s needs for information. Thus the second motive of this study is to explore the significance of guanxi for Chinese Facebook users in selecting the counterpart for information exchange. It is hoped that the results of this investigation will contribute to social networks, guanxi, information behaviour research and social network sites users’ study, especially in Taiwan. Based the data collected via online survey, this study found that respondents tend to rely on strong ties as their primary sources of information. If their strong ties were not able to provide the information, respondents would rely on the connections of these strong ties, rather than the weak ties in their network, to find the information they needed. Thus strong ties are the key to information exchange in a social network.

Word of mouth (WOM) communication has been a form of additional information for consumers wishing to make a purchase decision where there was uncertainty, lack of knowledge or just a general desire for more information. The increased access and use of social media as well as anonymous opportunities for consumers to provide their reviews on products or services is changing how WOM is used and sought. There is little research on the impact and use of WOM with respect to consumer decision making in a recreation and leisure context. Much research has been focussed on retail experiences and more tangible outcomes. The purpose of this study was to explore the process consumers undertake to seek out, listen and engage in WOM communication when making service purchase decisions. This study took place in a municipality in York Region that offered swimming lessons to the public. Participants were chosen using convenience sampling methodology. 500 surveys were distributed with 301 returned surveys completed to some degree. Study participants were recruited from observers watching a swim class offered by a municipal recreation provider. The survey instrument asked participants to describe themselves in terms of their experience level with municipal recreation programs. It also included three scales relating to susceptibility to influence, self confidence and need for cognition. Participants were exposed to one of five scenarios – one control message contained no treatment information and four scenarios with treatment messages relating to self-confidence and perceived risk. Treatment group members received information suggesting either high and low levels of perceived risk with purchase and high and low levels of self-confidence with knowledge (regarding the purchase decision). Respondents in this study possessed a very high level of self confidence in their program selections; they knew where to find the information and also how to explore program options. Overall this seemed a very well informed and confident group. Results suggest that susceptibility to influence (t = 5.889, p = .000) and self confidence (t = -2.174, p = .037) influenced their search for WOM communication. Need for cognition did not influence the likelihood they would seek WOM communication (t = -1.098, p = .280). Together all three variables explained 50% of the variance (adjusted R2 = .505) in the dependent variable (likelihood they would seek out WOM to make the purchase). These results indicate that participants were more likely to seek WOM when they were susceptible to influence and when their self confidence levels were low. Results also suggest that consumers were open to on line sources of word of mouth communication. More than that, study participants were generally willing to trust online reviews from people who were not necessarily known to them. As a result, online reviews could greatly influence the program registration numbers. A key question for future research could focus on the role shared experience plays in the evolution of trust between strangers. Many of these respondents would trust the advice of others simply because they reported having shared experience. How far does this trust go? How much risk must be present before they hesitate to take advice from unknown individuals? What are the characteristics or traits that consumers look for when assessing the validity of the reviews. Word of mouth seems a very pervasive and resilient concept. This may be particularly important in situations characterized by risk. Additional research could further explore the concept of word of finger and its influence on the traditional concept of WOM communication.

Anhand von Versuchsergebnissen wird gezeigt, dass Stahlbetonbauteile mit textilbewehrtem Beton verstärkt werden können. Sowohl die Torsionstragfähigkeit als auch die Gebrauchstauglichkeit werden durch die textilbewehrte Verstärkungsschicht deutlich verbessert. Vergleichsrechnungen zeigen, dass die Torsionstragfähigkeit mit bereits bekannten Stabwerksmodellen ermittelt werden kann.

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Introduction: Social networks have shown promise in curbing drug dependency and infectious diseases among marginalized populations. The purpose of this study is to elucidate how relationship strength in social networks is associated with risk behaviours for infectious diseases. Methods: Two reviews were conducted: 1) a systematic review exploring the association between risk behaviours and relationship strength 2) a review on the utilization of respondent driven sampling (RDS). We also analyzed network data to determine the association between recent injection drug use and recent crack use. Results: Our reviews revealed that few studies link relationship strength and risk behaviours; moreover, RDS is effective method of sampling from marginalized populations. Finally, our analysis demonstrated that close relationships are associated with drug use. Conclusion: “Close” relationships are important in arbitrating injection drug use and crack smoking. More research addressing the issues of using data from dynamic social processes and hard-to-reach populations is needed.

Word of mouth (WOM) communication has been a form of additional information for consumers wishing to make a purchase decision where there was uncertainty, lack of knowledge or just a general desire for more information. The increased access and use of social media as well as anonymous opportunities for consumers to provide their reviews on products or services is changing how WOM is used and sought. There is little research on the impact and use of WOM with respect to consumer decision making in a recreation and leisure context. Much research has been focussed on retail experiences and more tangible outcomes. The purpose of this study was to explore the process consumers undertake to seek out, listen and engage in WOM communication when making service purchase decisions. This study took place in a municipality in York Region that offered swimming lessons to the public. Participants were chosen using convenience sampling methodology. 500 surveys were distributed with 301 returned surveys completed to some degree. Study participants were recruited from observers watching a swim class offered by a municipal recreation provider. The survey instrument asked participants to describe themselves in terms of their experience level with municipal recreation programs. It also included three scales relating to susceptibility to influence, self confidence and need for cognition. Participants were exposed to one of five scenarios – one control message contained no treatment information and four scenarios with treatment messages relating to self-confidence and perceived risk. Treatment group members received information suggesting either high and low levels of perceived risk with purchase and high and low levels of self-confidence with knowledge (regarding the purchase decision). Respondents in this study possessed a very high level of self confidence in their program selections; they knew where to find the information and also how to explore program options. Overall this seemed a very well informed and confident group. Results suggest that susceptibility to influence (t = 5.889, p = .000) and self confidence (t = -2.174, p = .037) influenced their search for WOM communication. Need for cognition did not influence the likelihood they would seek WOM communication (t = -1.098, p = .280). Together all three variables explained 50% of the variance (adjusted R2 = .505) in the dependent variable (likelihood they would seek out WOM to make the purchase). These results indicate that participants were more likely to seek WOM when they were susceptible to influence and when their self confidence levels were low. Results also suggest that consumers were open to on line sources of word of mouth communication. More than that, study participants were generally willing to trust online reviews from people who were not necessarily known to them. As a result, online reviews could greatly influence the program registration numbers. A key question for future research could focus on the role shared experience plays in the evolution of trust between strangers. Many of these respondents would trust the advice of others simply because they reported having shared experience. How far does this trust go? How much risk must be present before they hesitate to take advice from unknown individuals? What are the characteristics or traits that consumers look for when assessing the validity of the reviews. Word of mouth seems a very pervasive and resilient concept. This may be particularly important in situations characterized by risk. Additional research could further explore the concept of word of finger and its influence on the traditional concept of WOM communication.

S’interroger sur l’adoption, dans un contexte d’évolution controversée des représentations de la parenté en Tunisie, oblige à s’attarder sur l'arrière plan social, culturel et juridique dans lequel elle s'inscrit. Le discours social sur l’adoption continue à promouvoir l’idée d’une bipartition de la parenté entre une parenté biologique, « de sang » ou « naturelle » et une parenté sociale, « affective »ou encore « du cœur ». A partir de témoignages de parents adoptifs et des adoptés, nous avons essayé de relever les différentes dimensions de l’épreuve d’adoption et des relations au sein de la parenté adoptive. L’étude des différents points soulevés permet d’emblée de questionner la place de la pluriparentalité à travers les pratiques et les représentations de la filiation adoptive dans un contexte socio-politique en mouvance. Elle permet en outre de déterminer le rapport entre la généalogie et la subjectivité dans le processus de la construction identitaire. / Questioning adoption, in a context of a controversial evolution of the representations of parenthood in Tunisia, compels one to dwell upon the social, cultural and legal backgrounds where it belongs. Social discourse on adoption continues to promote the idea of a dichotomy of parenthood, divided between biological parenthood - "blood" or "natural" parenthood- and social parenthood - "emotional" or "heart-based" parenthood. Based on accounts of adoptive parents and adoptees, we tried to identify the different dimensions of the experience of adoption and of the relationships within the adoptive parenthood. In building a relationship of adoption, representations appear as a primary mediator. The study of the various points raised directly questions the role of multi parenting through the practices and representations of adoptive kinship in a socio-political movement. It also allows to determine the relationship between genealogy and subjectivity in the process of identity construction.