A neural approach to evaluate the effect of lightning in power transformers

This paper proposes the application of computational intelligence techniques to assist complex problems concerning lightning in transformers. In order to estimate the currents related to lightning in a transformer, a neural tool is presented. ATP has generated the training vectors. The input variables used in Artificial Neural Networks (ANN) were the wave front time, the wave tail time, the voltage variation rate and the output variable is the maximum current in the secondary of the transformer. These parameters can define the behavior and severity of lightning. Based on these concepts and from the results obtained, it can be verified that the overvoltages at the secondary of transformer are also affected by the discharge waveform in a similar way to the primary side. By using the tool developed, the high voltage process in the distribution transformers can be mapped and estimated with more precision aiding the transformer project process, minimizing empirics and evaluation errors, and contributing to minimize the failure rate of transformers. © 2009 The Berkeley Electronic Press. All rights reserved.

Emerging adulthoods. Percorsi giovanili di partecipazione e cittadinanza in prospettiva intergenerazionale

La tesi tematizza come proprio oggetto di indagine i percorsi di partecipazione politica e civica dei giovani nei contesti di transizione alla vita adulta, concentrandosi sull’influenza delle relazioni tra generazioni su tali espressioni di coinvolgimento. L’approfondimento empirico consiste in una ricerca qualitativa condotta presso il quartiere Navile di Bologna nel 2012. Basandosi sull’approccio metodologico della grounded theory, essa ha coinvolto un campione di giovani e un campione di adulti per loro significativi attraverso interviste semistrutturate. Dall’analisi emerge una rilevante disaffezione giovanile nei confronti della politica che, tuttavia, non traduce in un rifiuto del coinvolgimento, ma in una “partecipazione con riserva” espressa attraverso atteggiamenti tutt’altro che passivi nei confronti della politica formale - basati sulla logica della riforma, della resistenza o della ribellione - e mediante un forte investimento in attività partecipative non convenzionali (associazionismo e coinvolgimento). A fare da sfondo all’interesse partecipativo dei giovani si colloca una lettura negativa della propria condizione presente ed un conseguente conflitto intergenerazionale piuttosto manifesto, che si riflette sulle stesse modalità di attivazione. La politica, nelle sue espressioni più strettamente formali, viene interpretata come un ‘territorio adulto’, gestito secondo logiche che lasciano poco spazio ai giovani i quali, per tale ragione, scelgono di attivarsi secondo modalità alternative in cui il confronto con l’altro, quando presente, avviene prevalentemente tra pari o su basi avvertite come più paritarie. Il distanziamento dei giovani dalla politica formale riflette quindi una parallela presa di distanza dagli adulti, i quali risultano smarriti nello svolgimento delle loro funzioni di modello e di riconoscimento. La loro ambivalenza rispetto ai giovani - ossia il continuo oscillare tra il profondo pessimismo e il cieco ottimismo, tra la guida direttiva e la deresponsabilizzazione - si traduce in un riconoscimento parziale delle reali potenzialità ed esigenze dei giovani come cittadini ed adulti emergenti.

Artists' advance: decreased upper alpha power while drawing in artists compared with non-artists

Brain mechanisms associated with artistic talents or skills are still not well understood. This exploratory study investigated differences in brain activity of artists and non-artists while drawing previously presented perspective line-drawings from memory and completing other drawing-related tasks. Electroencephalography (EEG) data were analyzed for power in the frequency domain by means of a Fast Fourier Transform (FFT). Low Resolution Brain Electromagnetic Tomography (LORETA) was applied to localize emerging significances. During drawing and related tasks, decreased power was seen in artists compared to non-artists mainly in upper alpha frequency ranges. Decreased alpha power is often associated with an increase in cognitive functioning and may reflect enhanced semantic memory performance and object recognition processes in artists. These assumptions are supported by the behavioral data assessed in this study and complement previous findings showing increased parietal activations in non-artists compared to artists while drawing. However, due to the exploratory nature of the analysis, additional confirmatory studies will be needed.

Towards a Variety of Family Models: Economic Contributions of Spouses and Family Power

In Western societies the increase in female employment (especially among married women) is seen as having brought about the crisis of the traditional model of the family, reinforcing the position of the "modern" model - the egalitarian family with two working spouses and a "dual-career" family. In contrast, the transitional situation in the post-communist countries during the 1990s is producing a crisis of the family with two working spouses (the basic type of the communist period) and leading to new power relations within the family. While the growth of dual-earner households in this century has implied modification of family models towards greater symmetry of responsibility for breadwinning and homemaking, there is considerable evidence that women's increased employment does not necessarily lead to a more egalitarian approach to gender roles within the family. The group set out to investigate the economic situation of families and economic power within the fame as a crucial factor in the transformation of families with two working spouses in order to reveal the specific patterns of gender contracts and power relations within the family that are emerging in response to the current political and economic transformation. They opted for a comparative approach, selecting the Czech Republic as a country where the very similar tendencies of a few years ago (almost 100% of women employed and the family as a realm of considerable private freedom where both women's and men's gender identities and the traditional distribution of family responsibilities were largely preserved) are combined with a very different experience in terms of economic inequalities during the 1990s to that of Russia. In the first stage of the study they surveyed 300 married couples (150 in each country) on the question of breadwinning. They then carried out in-depth interviews with 10 couples from each country (selected from among the educated layers of the population), focusing on the process of the social construction of gender, using breadwinning and homemaking as gender boundaries which distinguish men from women. By analysing changes in social position and the type of interpersonal interaction of spouses they distinguished two main types of family contracts: the neo-traditional "communal sharing" (with male breadwinner, traditional distribution of family chores and negotiated family power) and the modern one based on negotiated agreement. The most important pre-conditions of husband-wife agreement about breadwinning seemed to imply their overall gender ideology rather than the economic and/or family circumstances. In general, wives were more likely to express egalitarian views, supporting the blurring or even elimination of many gender boundaries. Husbands, on the other hand, more often gave responses calling for the continued maintenance of gender boundaries. The analysis showed that breadwinning is still an important gender boundary in these cultures, one that is assumed unless it is explicitly questioned and that is seen as part of what makes a man a "real man". The majority of respondents seemed to be committed to egalitarian ideology on gender roles and the distribution of family tasks, including decision making, but this is contradicted by the persistent idea of the husband as the breadwinner. This contradiction is more characteristic of the Russian situation than of the Czech. The quantitative study showed a difference in prevailing family models between the two countries, with a clearer shift towards the traditional family contract in the Russian case. The Czechs were more likely to consider their partnerships as based on negotiated agreement, while the Russians saw theirs as based on egalitarian contract, in both cases seeing this as the norm. The majority of couples said they felt satisfied with their marriage, although in both countries wives seemed to be less satisfied. There was however a difference in the issues that aroused dissatisfaction, with Czech women being more sensitive to issues such as self-realisation, personal independence, understanding and recognition in the family, and Russians to issues of love, understanding and recognition. The most disputed area for the majority of families was chores in the home, presumably because in many families both husband and wife were working hard outside the home and because a number of partners had differing views as to the ideal distribution of chores within the family. The distribution of power in the family seems to be linked to the level of well being. The analysis showed that in the dominant democratic model there is still an inverse connection between family leadership and well being: the more prominent the wife's position as head of the family is, the lower the level of family income. This may reflect both the husband's refusal to play the leading role in the family and even his rejection of any involvement in family issues in such a family. The qualitative research revealed that both men and women see the breadwinning role to be an essential part of masculine identity, a role which the female partner would take on temporarily to assist the male but not permanently since this would threaten the gender boundaries and the man's identity. At the same time, few breadwinners expressed a sense of job satisfaction and all considered their choice as imposed on them by the circumstances (i.e. having a family in difficult times). The group feel that family orientation and some loss of personal involvement in their profession is partly reflected in the fact that many of the men felt more comfortable and self-confident at home than at work. Women's work, on the other hand, was largely seen as a source of personal and self-realisation and social life. Eight out of ten of the Russian women interviewed were employed, although only two on a full-time basis, but none saw their jobs as adding substantially to the family budget. Both partners see the most important factor as the wife's wish to work or stay at home, and do not think it wise for the wife to work at the expense of her part of the "family contract", although husbands from the "egalitarian" relationships expressed more willingness to compromise. The analysis showed clearly that wives and husbands did not construct gender boundaries in isolation, with the interviews providing clear evidence of negotiation. At the same time, husbands' interpretations of their wives' employment were less susceptible to the influence of negotiation than were their gender attitudes and norms about breadwinning. One of the most interesting aspects of the spouses' negotiations was the extent to which they disagreed about what they seemed to have agreed upon. Most disagreements about the breadwinning boundaries, however, were over norms and were settled by changes in norms rather than in behavioural interpretation. Changes in norms were often a form of peace offering or were in response in changes in circumstances. The study did show, however, that many of the efforts at cooperation and compensation were more symbolic than real and the group found the plasticity of expressed gender ideology to be one of the most striking findings of their work. They conclude that the shift towards more traditional gednder distributions of incomes and domestic chores does not automatically mean the reestablishment of a patriarchal model of family power. On the contrary, it seems to be a compromise formation, relatively unstable, temporary and containing self-defeating forces as the split between the personal and professional value of work and its social value expressed in a money equivalent cannot be maintained for generations.

MODELING AND PROTOCOL DESIGN FOR EMERGING WIRELESS SYSTEMS

Mobile Mesh Network based In-Transit Visibility (MMN-ITV) system facilitates global real-time tracking capability for the logistics system. In-transit containers form a multi-hop mesh network to forward the tracking information to the nearby sinks, which further deliver the information to the remote control center via satellite. The fundamental challenge to the MMN-ITV system is the energy constraint of the battery-operated containers. Coupled with the unique mobility pattern, cross-MMN behavior, and the large-spanned area, it is necessary to investigate the energy-efficient communication of the MMN-ITV system thoroughly. First of all, this dissertation models the energy-efficient routing under the unique pattern of the cross-MMN behavior. A new modeling approach, pseudo-dynamic modeling approach, is proposed to measure the energy-efficiency of the routing methods in the presence of the cross-MMN behavior. With this approach, it could be identified that the shortest-path routing and the load-balanced routing is energy-efficient in mobile networks and static networks respectively. For the MMN-ITV system with both mobile and static MMNs, an energy-efficient routing method, energy-threshold routing, is proposed to achieve the best tradeoff between them. Secondly, due to the cross-MMN behavior, neighbor discovery is executed frequently to help the new containers join the MMN, hence, consumes similar amount of energy as that of the data communication. By exploiting the unique pattern of the cross-MMN behavior, this dissertation proposes energy-efficient neighbor discovery wakeup schedules to save up to 60% of the energy for neighbor discovery. Vehicular Ad Hoc Networks (VANETs)-based inter-vehicle communications is by now growingly believed to enhance traffic safety and transportation management with low cost. The end-to-end delay is critical for the time-sensitive safety applications in VANETs, and can be a decisive performance metric for VANETs. This dissertation presents a complete analytical model to evaluate the end-to-end delay against the transmission range and the packet arrival rate. This model illustrates a significant end-to-end delay increase from non-saturated networks to saturated networks. It hence suggests that the distributed power control and admission control protocols for VANETs should aim at improving the real-time capacity (the maximum packet generation rate without causing saturation), instead of the delay itself. Based on the above model, it could be determined that adopting uniform transmission range for every vehicle may hinder the delay performance improvement, since it does not allow the coexistence of the short path length and the low interference. Clusters are proposed to configure non-uniform transmission range for the vehicles. Analysis and simulation confirm that such configuration can enhance the real-time capacity. In addition, it provides an improved trade off between the end-to-end delay and the network capacity. A distributed clustering protocol with minimum message overhead is proposed, which achieves low convergence time.

A Wireless Charging System Applying Phase-Shift and Amplitude Control to Maximize Efficiency and Extractable Power

Wireless power transfer (WPT) is an emerging technology with an increasing number of potential applications to transfer power from a transmitter to a mobile receiver over a relatively large air gap. However, its widespread application is hampered due to the relatively low efficiency of current Wireless power transfer (WPT) systems. This study presents a concept to maximize the efficiency as well as to increase the amount of extractable power of a WPT system operating in nonresonant operation. The proposed method is based on actively modifying the equivalent secondary-side load impedance by controlling the phase-shift of the active rectifier and its output voltage level. The presented hardware prototype represents a complete wireless charging system, including a dc-dc converter which is used to charge a battery at the output of the system. Experimental results are shown for the proposed concept in comparison to a conventional synchronous rectification approach. The presented optimization method clearly outperforms state-of-the-art solutions in terms of efficiency and extractable power.

Combined desalination and power generation using coal energy.

Phase I report. Site selection and estimated water costs based on current technology. Phase II report. Investigation of emerging technology, by-product recovery, and very large capacities. Period of performance: June 1965-Oct. 1966.

RSA-Grid: A grid computing based framework for power system reliability and security analysis

Grid computing is an emerging technology for providing the high performance computing capability and collaboration mechanism for solving the collaborated and complex problems while using the existing resources. In this paper, a grid computing based framework is proposed for the probabilistic based power system reliability and security analysis. The suggested name of this computing grid is Reliability and Security Grid (RSA-Grid). Then the architecture of this grid is presented. A prototype system has been built for further development of grid-based services for power systems reliability and security assessment based on probabilistic techniques, which require high performance computing and large amount of memory. Preliminary results based on prototype of this grid show that RSA-Grid can provide the comprehensive assessment results for real power systems efficiently and economically.

Design Strategies and Modelling of Low-Power Sigma-Delta Analog-to-Digital Converters

Oggi, i dispositivi portatili sono diventati la forza trainante del mercato consumer e nuove sfide stanno emergendo per aumentarne le prestazioni, pur mantenendo un ragionevole tempo di vita della batteria. Il dominio digitale è la miglior soluzione per realizzare funzioni di elaborazione del segnale, grazie alla scalabilità della tecnologia CMOS, che spinge verso l'integrazione a livello sub-micrometrico. Infatti, la riduzione della tensione di alimentazione introduce limitazioni severe per raggiungere un range dinamico accettabile nel dominio analogico. Minori costi, minore consumo di potenza, maggiore resa e una maggiore riconfigurabilità sono i principali vantaggi dell'elaborazione dei segnali nel dominio digitale. Da più di un decennio, diverse funzioni puramente analogiche sono state spostate nel dominio digitale. Ciò significa che i convertitori analogico-digitali (ADC) stanno diventando i componenti chiave in molti sistemi elettronici. Essi sono, infatti, il ponte tra il mondo digitale e analogico e, di conseguenza, la loro efficienza e la precisione spesso determinano le prestazioni globali del sistema. I convertitori Sigma-Delta sono il blocco chiave come interfaccia in circuiti a segnale-misto ad elevata risoluzione e basso consumo di potenza. I tools di modellazione e simulazione sono strumenti efficaci ed essenziali nel flusso di progettazione. Sebbene le simulazioni a livello transistor danno risultati più precisi ed accurati, questo metodo è estremamente lungo a causa della natura a sovracampionamento di questo tipo di convertitore. Per questo motivo i modelli comportamentali di alto livello del modulatore sono essenziali per il progettista per realizzare simulazioni veloci che consentono di identificare le specifiche necessarie al convertitore per ottenere le prestazioni richieste. Obiettivo di questa tesi è la modellazione del comportamento del modulatore Sigma-Delta, tenendo conto di diverse non idealità come le dinamiche dell'integratore e il suo rumore termico. Risultati di simulazioni a livello transistor e dati sperimentali dimostrano che il modello proposto è preciso ed accurato rispetto alle simulazioni comportamentali.

Organohalogen contaminants in wildlife from the Yangtze River Delta : Development of methods and assessments of legacy and emerging persistent organic pollutants

Rapid economic development has occurred during the past few decades in China with the Yangtze River Delta (YRD) area as one of the most progressive areas. The urbanization, industrialization, agricultural and aquaculture activities result in extensive production and application of chemicals. Organohalogen contaminants (OHCs) have been widely used as i.e. pesticides, flame retardants and plasticizers. They are persistent, bioaccumulative and pose a potential threat to ecosystem and human health. However, limited research has been conducted in the YRD with respect to chemicals environmental exposure. The main objective of this thesis is to investigate the contamination level, distribution pattern and sources of OHCs in the YRD. Wildlife from different habitats are used to indicate the environmental pollution situation, and evaluate selected matrices for use in long term biomonitoring to determine the environmental stress the contamination may cause. In addition, a method is developed for dicofol analysis. Moreover, a specific effort is made to introduce statistic power analysis to assist in optimal sampling design. The thesis results show extensive contamination of OHCs in wildlife in the YRD. The occurrences of high concentrations of chlorinated paraffins (CPs) are reported in wildlife, in particular in terrestrial species, (i.e. short-tailed mamushi snake and peregrine falcon). Impurities and byproducts of pentachlorophenol products, i.e. polychlorinated diphenyl ethers (PCDEs) and hydroxylated polychlorinated diphenyl ethers (OH-PCDEs) are identified and reported for the first time in eggs from black-crowned night heron and whiskered tern. High concentrations of octachlorodibenzo-p-dioxin (OCDD) are determined in these samples. The toxic equivalents (TEQs) of polychlorinated dibenzo-p-dioxin (PCDDs) and polychlorinated dibenzofurans (PCDFs) are at mean levels of 300 and 520 pg TEQ g-1lw (WHO2005 TEQ) in eggs from the two bird species, respectively. This is two orders of magnitude higher than European Union (EU) regulation limit in chicken eggs. Also, a novel pattern of polychlorinated biphenyls (PCBs) with octa- to decaCBs, contributing to as much as 20% of total PCBs therein, are reported in birds. The legacy POPs shows a common characteristic with relatively high level of organochlorine pesticides (i.e. DDT, hexacyclohexanes (HCHs) and Mirex), indicating historic applications. In contrast, rather low concentrations are shown of industrial chemicals such as PCBs and polybrominated diphenyl ethers (PBDEs). A refined and improved analytical method is developed to separate dicofol from its major decomposition compound, 4,4’-dichlorobenzophenone. Hence dicofol is possible to assess as such. Statistic power analysis demonstrates that sampling of sedentary species should be consistently spread over a larger area to monitor temporal trends of contaminants in a robust manner. The results presented in this thesis show high CPs and OCDD concentrations in wildlife. The levels and patterns of OHCs in YRD differ from other well studied areas of the world. This is likely due to the extensive production and use of chemicals in the YRD. The results strongly signal the need of research biomonitoring programs that meet the current situation of the YRD. Such programs will contribute to the management of chemicals and environment in YRD, with the potential to grow into the human health sector, and to expand to China as a whole.

Strategizing networks of power and influence:the internet and the struggle over contested space

Whilst some authors have portrayed the Internet as a powerful tool for business and political institutions, others have highlighted the potential of this technology for those vying to constrain or counter-balance the power of organizations, through e-collectivism and on-line action. What appears to be emerging is a contested space that has the potential to simultaneously enhance the power of organizations, whilst also acting as an enabling technology for the empowerment of grass-root networks. In this struggle, organizations are fighting for the retention of “old economy” positions, as well as the development of “new economy” power-bases. In realizing these positions, organizations and institutions are strategizing and manoeuvering in order to shape on-line networks and communications. For example, the on-line activities of individuals can be contained through various technological means, such as surveillance, and the structuring of the virtual world through the use of portals and “walled gardens”. However, loose groupings of individuals are also strategizing to ensure there is a liberation of their communication paths and practices, and to maintain the potential for mobilization within and across traditional boundaries. In this article, the unique nature and potential of the Internet are evaluated, and the struggle over this contested virtual space is explored.

The dynamics of organizational change : an analysis of power, professions and new managerialism in the case of CoastElectric

It is widely accepted that the Thatcher years and their immediate aftermath were associated with substantive social and organizational change. The privatisation programme, 'the rolling back of the State', prosecuted by the successive Conservative Governments from 1979-1997 was a central pillar of Governmental policy. This thesis seeks to engage with privatization through the of CoastElectric, a newly privatised Regional Electricity Company. This thesis contributes to the extant understanding of the dynamics of organizational change in four major ways. Firstly, the study into CoastElectric addresses the senior management decision making within the organization: in particular, it will attempt to make sense of 'why' particular decisions were made. The theoretical backdrop to this concern will draw on the concepts of normalization, cultural capital and corporate fashion. The argument presented in this thesis is that the decision-making broadly corresponded with that which could be considered to be at the vanguard of mangerialist thought. However, a detailed analysis suggested that at different junctures in CoastElectric's history there were differences in the approach to decision making that warranted further analysis. The most notable finding was that the relative levels of new managerialist cultural capital possessed by the decision-making elite had an important bearing upon whether the decision was formulated either endogenously or exogenously, with the assistance of cultural intermediaries such as management consultants. The thesis demonstrates the importance of the broader discourse of new managerialism in terms of shaping what is considered to be a 'commonsensical, rational' strategy. The second concern of this thesis is that of the process of organizational change. The study of CoastElectric attempts to provide a rich account of the dynamics of organizational change. This is realized through, first, examining the pre-existing context of the organization; second, through analyzing the power politics of change interventions. The master concepts utilised in this endeavour are that of: dividing practices, the establishment of violent hierarchies between competing discourses; symbolic violence; critical turning points; recursiveness; creative destruction; legitimation strategies and the reconstitution of subjects in the workplace.

Human resource management in emerging markets:an introduction

The shifting of global economic power from mature, established markets to emerging markets (EMs) is a fundamental feature of the new realities in the global political economy. Due to a combination of reasons (such as scarcity of reliable information on management systems of EMs, the growing contribution of human resource management (HRM) towards organisational performance, amongst others), the understanding about the dynamics of management of HRM in the EMs context and the need for proactive efforts by key stakeholders (e.g., multinational and local firms, policy makers and institutions such as trade unions) to develop appropriate HRM practice and policy for EMs has now become more critical than ever. It is more so given the phenomenal significance of the EMs predicted for the future of the global economy. For example, Antoine van Agtmael predicts that: in about 25 years the combined gross national product (GNP) of emergent markets will overtake that of currently mature economies causing a major shift in the centre of gravity of the global economy away from the developed to emerging economies. (van Agtmael 2007: 10–11) Despite the present (late 2013 and early 2014) slowdown in the contribution of EMs towards the global industrial growth (e.g., Das, 2013; Reuters, 2014), EMs are predicted to produce 70 per cent of world GDP growth and a further ten years later, their equity market capitalisation is expected to reach US$ 80 trillion, 1.2 times more than the developed world (see Goldman Sachs, 2010).

Real-time temperature estimation for power MOSFETs considering thermal ageing effects

This paper presents a novel real-time power-device temperature estimation method that monitors the power MOSFET's junction temperature shift arising from thermal aging effects and incorporates the updated electrothermal models of power modules into digital controllers. Currently, the real-time estimator is emerging as an important tool for active control of device junction temperature as well as online health monitoring for power electronic systems, but its thermal model fails to address the device's ongoing degradation. Because of a mismatch of coefficients of thermal expansion between layers of power devices, repetitive thermal cycling will cause cracks, voids, and even delamination within the device components, particularly in the solder and thermal grease layers. Consequently, the thermal resistance of power devices will increase, making it possible to use thermal resistance (and junction temperature) as key indicators for condition monitoring and control purposes. In this paper, the predicted device temperature via threshold voltage measurements is compared with the real-time estimated ones, and the difference is attributed to the aging of the device. The thermal models in digital controllers are frequently updated to correct the shift caused by thermal aging effects. Experimental results on three power MOSFETs confirm that the proposed methodologies are effective to incorporate the thermal aging effects in the power-device temperature estimator with good accuracy. The developed adaptive technologies can be applied to other power devices such as IGBTs and SiC MOSFETs, and have significant economic implications.

Irrelevant or transformative power? The OECD DAC and foreign aid policies in Central and Eastern Europe

The paper examines the impact of the OECD’s Development Assistance Committee (DAC) on the emerging foreign aid policies of the Central and Eastern European (CEEs) countries. The Czech Republic, Poland, Slovakia and Slovenia joined the DAC in 2013, and the committee has aimed to socialise them into the norms of the international development system. Generally, however, there is little evidence of impact due to the soft nature of the DAC’s policy recommendations, and the fact that the committee, reacting to the challenges to its legitimacy from non-Western donors, has become much less demanding towards potential members than in the past. The paper, however, argues that one must examine the processes of how the norm and policy recommendations of the DAC are mediated domestically. The case of the Czechepublic’s reforms in its foreign aid policy between 2007 and 2010 shows that domestic actors can use the OECD strategically to build support for their own cause and thus achieve seemingly difficult policy reform.