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In electromagnetic transient studies, only a small part of an AC power system can be modeled in detail. The remaining parts of the system should be reduced to equivalent model. This study presents an approach for obtaining network equivalents for ac power systems using QZ algorithm. The proposed method obtains accurate resonant frequencies directly from the system equations to be used in finding the network equivalent parameters. Also, the proposed method is a useful tool to predict the system response and has the following advantages. It has less complexity because it obtains the minima and maxima frequencies directly from the system equations. It gives reliable prediction and complete information about behavior of the test system and its peaks and troughs before calculating its frequency response. The proposed method determines the accurate value for resistors of the network equivalent model as the real part of the impedance function magnitude at the minima frequency points. In this study, a general algorithm is developed to determine the frequency dependent network equivalent model parameters for any given system. Finally, this method is implemented on Hormozgan network as a part of Iran electric power network and the parameters of equivalent circuit are calculated.

Climate plays an important role in human health and it is well established that climate change can have very significant impacts in this regard. In partnership with The Lancet and the MJA, we present the inaugural Australian Countdown assessment of progress on climate change and health. This comprehensive assessment examines 41 indicators across five broad sections: climate change impacts, exposures and vulnerability; adaptation, planning and resilience for health; mitigation actions and health co-benefits; economics and finance; and public and political engagement. These indicators and the methods used for each are largely consistent with those of the Lancet Countdown global assessment published in October 2017, but with an Australian focus. Significant developments include the addition of a new indicator on mental health. Overall, we find that Australia is vulnerable to the impacts of climate change on health, and that policy inaction in this regard threatens Australian lives. In a number of respects, Australia has gone backwards and now lags behind other high income countries such as Germany and the United Kingdom. Examples include the persistence of a very high carbon-intensive energy system in Australia, and its slow transition to renewables and low carbon electricity generation. However, we also find some examples of good progress, such as heatwave response planning. Given the overall poor state of progress on climate change and health in Australia, this country now has an enormous opportunity to take action and protect human health and lives. Australia has the technical knowhow and intellect to do this, and our annual updates of this assessment will track Australia's engagement with and progress on this vitally important issue.

Lignocellulose biomass derived from plant cell walls is a rich source of biopolymers, chemicals, and sugars, besides being a sustainable alternative to petrochemicals. A natural armor protecting living protoplasts, the cell wall is currently the target of intense study because of its crucial importance in plant development, morphogenesis, and resistance to (a)biotic stresses. Beyond the intrinsic relevance related to the overall plant physiology, plant cell walls constitute an exquisite example of a natural composite material that is a constant source of inspiration for biotechnology, biofuel, and biomaterial industries. The aim of the present review is to provide the reader with an overview of the current knowledge concerning lignocellulosic biomass synthesis and degradation, by focusing on its three principal constituents, i.e. cellulose, hemicellulose (in particular xylan), and lignin. Furthermore, the current industrial exploitation of lignocellulose from fast growing fibre crops (such as hemp) is highlighted. We conclude this review by suggesting approaches for further research to fill gaps in our current knowledge and to highlight the potential of biotechnology and bioengineering in improving both biomass biosynthesis and degradation.

AbstractSeveral nitrones and one nitroso compound have been evaluated for their ability to control the molecular weight of polystyrene via the recently introduced radical polymerization method of enhanced spin capturing polymerization (ESCP). In this technique, molecular weight control is achieved (at ambient or slightly elevated temperatures) via the reaction of a growing radical chain with a nitrone forming a macronitroxide. These nitroxides subsequently react rapidly and irreversibly with propagating macroradicals forming polymer of a certain chain length, which depends on the nitrone concentration in the system. Via evaluation of the resulting number‐average molecular weight, Mn, at low conversions, the addition rate coefficient of the growing radicals onto the different nitrones is determined and activation energies are obtained. For the nitrones N‐tert‐butyl‐α‐phenylnitrone (PBN), N‐methyl‐α‐phenylnitrone (PMN), and N‐methyl‐α‐(4‐bromo‐phenyl) nitrone (pB‐PMN), addition rate coefficients, kad,macro, in a similar magnitude to the styrene propagation rate coefficient, kp, are found with spin capturing constants CSC (with CSC = kad,macro/kp) ranging from 1 to 13 depending on the nitrone and on temperature. Activation energies between 23.6 and 27.7 kJ mol−1 were deduced for kad,macro, congruent with a decreasing CSC with increasing temperature. Almost constant Mn over up to high monomer to polymer conversions is found when CSC is close to unity, while increasing molecular weights can be observed when the CSC is large. From temperatures of 100 °C onward, reversible cleavage of the alkoxyamine group can occur, superimposing a reversible activation/deactivation mechanism onto the ESCP system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1098–1107, 2009

Abstract Application of highly absorptive construction materials is proved to be one of leading causes of urban overheating in big cities. To avoid the excessive heat by the conventional construction materials, several advanced heat-rejecting coating technologies were developed during the last decades. The main idea behind heat-rejecting coatings is to have colder coatings with the same appearance and colour of conventional coatings. One of the existing technologies for heat-rejecting coatings are advanced coatings with high solar reflection in the infrared range or so-called cool coatings. Recently, re-emission of the visible-range light by nano-scale semiconductors, known as Quantum Dots (QDs), were introduced as another effective heat-rejecting technology. In this paper, we showed that QDs also demonstrate a very high solar transmission in the near-infrared range, and therefore, a highly near-infrared reflective base layer can significantly improve their cooling potential. The high transmission value in the near-infrared range is due to the low absorption coefficient in the wavelengths longer than absorption edge wavelength (i.e. the wavelength corresponding to the bandgap energy) in semiconductors. We show that surface temperature reduction potential of CdSe/ZnS QDs film through fluorescent cooling is about 2.5 °C, which could be increased by another 8.1 °C with a highly near-infrared reflective base layer in a typical sunny day.

In this paper, we explore the practices and spaces of mobile phone charging in The Gambia and Sierra Leone through the lens of 'electricity scarcity‘ as a means to conceptualise electricity access in West Africa. The International Energy Agency (IEA) is seen as the leading authority on the state of global energy access, and is frequently cited by government and non-government bodies. We, however, suggest that the IEA‘s quantitative and binary framing of electricity access is analytically problematic for understanding energy poverty. Using ethnographic methods, including observation and semi-structured interviews, we provide insights into the changing socio-technological, socio-political and socio-economic dimensions of mobile phone charging including its relationship with the built environment. Comparing mobile phone charging in The Gambia and Sierra Leone, clearly shows that the notion of absolute electricity scarcity which is promulgated by IEA statistics only offers a limited picture of energy poverty, especially at the locale. Instead, drawing on political ecology scholarship, we propose a concept of political electricity scarcity as an approach enables a more human-centred and nuanced understanding of how energy poverty operates or is mitigated through community-based structures or at a household level. By reframing energy poverty issues through this lens, we are able to illustrate the role that political economy dynamics play in shaping the electricity flows in rural Sub-Saharan Africa and who ultimately gets what kind of electricity access.

The creep of materials is a research topic of major significance in the life assessment and design of many modern engineering components of advance technology such as: power generation plant, chemical plant, gas turbines, jet engines, spacecrafts, components made of plastics and polymers, etc. To predict the creep life of such components, one necessary ingredient is a creep damage model. The current creep damage models are either too cumbersome to be readily employed and/or not sufficiently accurate for practical applications. This paper describes a new multiaxial creep damage model that alleviates the major shortcomings of the existing models yet it is simple and accurate enough to be readily applicable to industrial cases.