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Epidemiological studies indicate that electromagnetic fields (EMF) are associated with cancer in humans. Exposure to mobile phone specific high frequency fields (HF-EMF) may lead to increased glioma risks, while low frequency radiation (LF-EMF) is associated with childhood leukemia. We studied the impact of HF-EMF (1950 MHz, UMTS signal) on DNA stability in an astrocytoma cell line (1321N1), and the effect of LF-EMF (50 Hz) in human derived lymphoma (Jurkat) cells. To find out if these fields affect chemically induced DNA damage, co-exposure experiments were performed. The cells were exposed to HF-EMF or LF-EMF and treated simultaneously and sequentially with mutagens. The compounds cause DNA damage via different molecular mechanisms, i.e. pyrimidine dimers which are characteristic for UV light (4-nitroquinoline 1-oxide, 4NQO), bulky base adducts (benzo[ a ]pyrene diolepoxide, BPDE), DNA-DNA and DNA-protein cross links and oxidative damage (NiCl 2 , CrO 3). DNA damage was measured in single cell gel electrophoresis (comet) assays. We found a moderate reduction of basal and 4NQO-induced DNA damage in the astrocytoma line, but no significant alterations of chemically induced DNA migration by the HF and LF fields under all other experimental series. The biological consequences of the moderate reduction remain unclear, but our findings indicate that acute mobile phone and power line specific EMF exposures do not enhance genotoxic effects caused by occupationally relevant chemical exposures. • Mobile phone-specific (HF) and low-frequency (LF) electromagnetic fields (EMF) may cause cancer. • We investigated the impact of these fields on DNA damage in human-derived cells. • The cells were exposed to the EMF in combination with occupationally related carcinogens. • We found no evidence for synergistic effects. • In neural cells, we observed a significant reduction of DNA damage after exposure to the HF field. [ABSTRACT FROM AUTHOR]

Norway aims to transform into a low-emission nation by 2050. However, the energy transition comes with challenges, as expanding renewable energy infrastructure requires significant land areas, which raises concerns about associated environmental impacts, particularly on species richness. The first system-wide life cycle assessment (LCA) approach that integrates multiple biodiversity models is presented, evaluating the current effects of renewable energy production and transmission in Norway. The impacts of Norwegian hydropower and onshore wind power plants are quantified, which contribute 98% of Norway's electricity generation. Additionally, the effects of power lines are included to assess the spatial origins of the biodiversity impacts derived from both energy production and transmission relative to where electricity was transmitted to and consumed in Norway. The analyses show that hydropower exerts the most substantial impact on species richness and that the electric grid affects mostly mammal richness due to habitat conversion and fragmentation. As energy production primarily originates in western-central and northern Norway, regions with low electricity generation, such as south-east Norway, import a substantial share of the biodiversity impacts for their energy consumption. However, integrating an international dimension is crucial, as multiple European countries exchange energy with Norway, and thus also contribute to the pressure on local species richness. The results present the current operational impacts on biodiversity caused by Norway's electricity system. Since Norway intends to increase its renewable energy production capacity in the coming decades, this approach can serve as an instrument for developing scenarios to assess the future construction of hydropower, onshore wind power, and power lines. It can help shape Norway's energy future, ensuring a holistic approach that integrates impacts on species diversity and promotes an environmentally friendly energy transition. While focused on Norway, the methodology is adaptable to other regions if the required data is available. • First comparable LCIA approach quantifying biodiversity impacts of energy systems. • System-wide assessment of Norwegian hydropower, wind power, and power lines. • Hydropower has the largest overall biodiversity impact in Norway. • Electricity transmission severely contributes to habitat loss and fragmentation. • Models adaptable for other regions with relevant input data. [ABSTRACT FROM AUTHOR]

There is an increasing expectation for companies to revise their activities to minimize impacts on biodiversity, as well as undertake compensatory and proactive actions to restore biodiversity. To contribute towards global biodiversity goals, such actions need to be both ambitious and effective. Yet, implementation of mitigation actions to avoid impact is often poor or omitted, and actions to minimize and restore can be of varying effectiveness. The financial costs of actions are often seen as a barrier. Here we argue that mitigation costs, both costs incurred or avoided, are often overlooked or over-simplified when designing mitigation strategies. This includes limited quantification of management costs, the costs of potential impacts, assumed counterfactuals (i.e., what would happen without mitigation?), the distribution of costs between stakeholders, and the value gained by enhancing biodiversity. A more detailed and nuanced understanding of the economic costs and benefits of mitigation actions can both help prioritize resources more efficiently and reveal the true cost-effectiveness of mitigation at the project and portfolio levels, particularly for actions that avoid damage to biodiversity. This could improve the implementation of the mitigation hierarchy, as project developers or decision makers have a better understanding of the actual costs and benefits of different potential mitigation strategies. We exemplify this thinking with a detailed case study that determines the costs and effectiveness of a range of actions to reduce bird collisions on power lines. • Understanding the costs of actions is important for efficient conservation. • Yet, costs can often be neglected during mitigation hierarchy application. • A detailed, nuanced assessment of costs influences cost-effectiveness estimates. • We demonstrate this with a case study of power line impacts on bird species. • We discuss opportunities and implications for mitigation decision making. [ABSTRACT FROM AUTHOR]

• We assessed anthropogenic impacts on territorial species using individual based models. • Impacts increased when exposure to anthropogenic mortality affected multiple territories. • Impacts increased when mortality affected both territorial and non-territorial individuals. • Mitigation actions should account for territorial and non-territorial birds. • Our IBM framework can inform strategies to mitigate impacts of anthropogenic mortality. Wildlife anthropogenic mortality is increasing worldwide, yet there is limited understanding regarding its population-level impacts. Territorial species stand out in this context, as they possess distinctive characteristics that are often overlooked but may significantly affect their vulnerability. In particular, population impacts may depend on the level and spatial distribution of additional mortality risk across territories, and on the extent to which exposure to increased mortality varies across life stages (i.e., territorial and non-territorial individuals). In this study, we developed an Individual-Based Model (IBM) to explore these issues, using the Bonelli's eagle (Aquila fasciata) and electrocution in powerline pylons as a model system. We used declines in annual population growth rates as a proxy for negative impacts, and conducted simulations to estimate the relative impacts of different levels of mortality risk, the spatial pattern of such risks, and the risk exposure of different life stages. Population-level impacts greatly increased with the mortality risks simulated, and they were lower when exposure to mortality risks was concentrated versus spread across territories. Impacts were highest when both territorial and non-territorial individuals were exposed to anthropogenic mortality risks, and they were higher when such exposure only affected non-territorial versus territorial individuals. Our results underscore that each breeding territory should be considered as a unit, where all existing pylons should be intervened whenever mitigation actions are put in place. Results also highlight the importance of considering both the territorial and non-territorial fractions of the population to prevent and mitigate the impacts of increased mortality. More generally, our study illustrates the value of IBM frameworks such as ours to explore population-level impacts resulting from anthropogenic mortality in territorial species, and to inform the development of conservation strategies to mitigate such impacts. [ABSTRACT FROM AUTHOR]

The widespread popularity of unmanned aerial vehicles enables an immense amount of power line inspection data to be collected. It is an urgent issue to employ massive data especially the visible images to maintain the reliability, safety, and sustainability of power transmission. To date, substantial works have been conducted on the data analysis for power line inspection. With the aim of providing a comprehensive overview for researchers interested in developing a deep-learning-based analysis system for power line inspection data, this paper conducts a thorough review of the current literature and identifies the challenges for future study. Following the typical procedure of data analysis in power line inspection, current works in this area are categorized into component detection and fault diagnosis. For each aspect, the techniques and methodologies adopted in the literature are summarized. Valuable information is also included such as data description and method performance. In particular, an in-depth discussion of existing deep-learning-based analysis methods of power line inspection data is proposed. To conclude the paper, several study trends for the future in this area are presented including data quality problems, small object detection, embedded application, and evaluation baseline. [ABSTRACT FROM AUTHOR]

The interaction between wildlife and power lines has collateral effects that include wildfires and Carbon Dioxide (CO 2 ) emissions. However, currently available information is scarce and so new approaches are needed to increase our understanding of this issue. Here, we present the first analysis of wildfires and their incidence as a result of this interaction in Spain during the period 2000–2012. Amongst the 2788 Power-Line Mediated Wildfires (PLMW recorded) during this period, 30 records of Fauna Mediated Wildfires (FMW) were found, with an average affected vegetation cover of 9.06 ha. Our findings suggest that no significant differences were observed between the amount of affected surface area due to fauna mediated wildfires and power-line mediated wildfires. In both cases, a space-grouping trend was observed. In terms of changing trends over time, after the first incident detected in 2005, the number of incidents increased until 2008, year in which the percentage of wildfires caused by wildlife stabilized at approximately 2.4% of all power-line-induced wildfires. Population density and road abundance were variables that better explained PLMW whereas for FMW, the models that included land use and raptor abundance. In the multivariate model, FMW emergence was positively related with population density, percentage of grazing areas and Natura 2000 cover, and predatory abundance; and negatively with the percentage of forested area. No significant differences were observed between the species of birds that caused wildfires and the species of ringed birds killed by electrocution. The economic and environmental impact due to necessary repairs, the loss of biodiversity and CO 2 emissions represent an estimated net value of €7.6–12.4 M for the period 2000–2012, which indicates the importance of the economic and environmental costs associated with wildfires. [ABSTRACT FROM AUTHOR]

Anthropogenic threats to Hawaii's birds have resulted in numerous extinctions with many additional species now listed as threatened or endangered. Implementing conservation recovery plans for these birds requires identifying a comprehensive list of threats. Research from outside of Hawaii has shown that avian powerline collisions are one of the greatest anthropogenic causes of mortality. To date, with the exception of endangered seabirds, powerline collisions have not been considered a major threat to most native and endangered birds in Hawaii. This may be because Hawaiian species face a multitude of already identified threats with the clearest causes of mortality (e.g., vehicle collisions) often obscuring evidence of powerline collisions. We report a strong spatial correlation between roads and powerlines which increases the likelihood that birds colliding with powerlines are grounded on roads, where secondary vehicle collisions can confound the primary grounding cause. We recorded flight heights of all birds at powerlines and roads, as well as the frequency of flights directly at powerline and vehicle height. We observed 162 powerline collisions across ten native and endemic birds. We also collected a further 251 grounded native and endangered birds. For each of the grounded birds we evaluated the injuries the bird sustained and the grounding location itself using multiple factors to attribute the primary cause of grounding. Using this system, we classified these birds as follows - powerline collision (69.3%), vehicle strike (9.2%), and uncertain cause of grounding (21.5%). Overall, we confirm that 13 native and endangered species collided with powerlines, including all native and endemic waterbirds, and vehicle collisions were confirmed for three species. Our study clearly demonstrates that birds hitting powerlines can be grounded in roads and then secondarily run over by vehicles, which can obscure the primary cause of grounding. The obfuscation of powerline collision by secondary vehicle strike has previously prevented researchers and managers from identifying powerline collisions as a threat to native and endemic waterbirds. By using the data reported here, the local power company has implemented 170 km of bird-friendly powerline modifications including the removal of static lines, attachment of bird diverters and reconfigurations. These bird-friendly powerline modifications are the first of their kind in the state of Hawaii. [ABSTRACT FROM AUTHOR]

The use of systematic area-selection procedures to design protected areas can help optimize conservation actions. However, this process has rarely been used to identify high-risk mortality areas to protect wildlife from human impacts. Electrocution on power lines is one the most important human-related causes of bird mortality worldwide, especially for raptors. Identifying and correcting dangerous individual pylons can significantly reduce the number of electrocution victims, but applying this procedure at a large spatial scale is impractical. In this paper we describe a new selection process that allows for identification of high-risk mortality areas at large scales, combining spatial electrocution risk models with maps of species sensitivity to such an impact. We used the Valencia Region (eastern Spain) as our study system. The risk prediction map was built using bird electrocution records on 1 km × 1 km grids from 2000 to 2009 and the species sensitivity map was built using data on presence and use of four raptor species. The combination of both maps was compared to the distribution of Special Protected Areas and validated by local experts to identify prediction errors or gaps. The final proposal of high priority areas to protect birds from electrocution covered 16.3% of the Valencia Region. Our work supports the use of predictive models and sensitivity maps in the decision-making process to locate high priority infrastructure-related wildlife protection areas at a large scale. [ABSTRACT FROM AUTHOR]

The inspection and maintenance of electrical power lines (PL) via unmanned aerial vehicles (UAV) require fast and accurate PL detection to ensure smooth and secure electrical operations. However, the detection of PLs from aerial images is a highly challenging task due to the thin nature of PLs and the inherent noisy image backgrounds. Traditional line and edge detection methods do not detect the PLs accurately due to the cluttered backgrounds while the more recent deep learning (DL) CNNs are also not feasible for efficient PL detection due to the coarse bounding boxes and the computationally expensive pixel-based segmentations. Hence, in this study we propose PLPose, a novel framework for detecting the PLs via key points-based pose estimation technique and adapt the MobileNetV3 CNN for this task (kMobileNetV3), by adding a simple key point detection head to predict the PL key points. We also introduce a novel data-centric architecture (kMobileNetV3 + UDP), by adding the unbiased data processing (UDP) module to our kMobileNetV3, for faster and more accurate key point-based PL detection along with novel methods for data annotations and performance evaluation. Evaluations of PLPose on three benchmark PL datasets (PLDM, PLDU and the Mendeley Powerline Dataset) reveal that our proposed framework outperforms the state-of-the-art top-down pose estimation networks (HRNet-w32, HRNet-w32 + UDP and Resnet-50 Simple Baselines) in processing speed (∼29 FPS) and model size (5.23 M) for PL detection. Thus, the comprehensive experimental results demonstrate the effectiveness of our proposed framework. Our code is available from Github (https://www.github.com/rubeea/pl_mmpose). [ABSTRACT FROM AUTHOR]

Exposure to low-frequency electromagnetic fields (EMF) has become an issue considering a number of high-power low-frequency EMF sources installed in residential environment. Therefore, the EMF monitoring and appropriate exposure assessment are highly important regarding the safety, since residents can spend considerable time in the vicinity of such high-power objects. This short paper brings the case study related to the broadband continuous monitoring of the low-frequency magnetic field in the vicinity of the outdoor power substation, as a particularly important and interesting EMF source. Moreover, the exposure assessment of the general population, performed by a newly proposed adaptive boundary exposure approach, is presented. This approach assesses the upper and lower daily exposure boundaries, offering the range where real exposure is positioned. The reduction of difference between boundaries can be attained by frequency spectrum analysis, while in this case study the initial boundary difference was reduced from 99.6% to 33.3%. [ABSTRACT FROM AUTHOR]

The growing increase in frequency and intensity of extreme weather events (EWEs) has a wide impact on energy systems and consumers, as energy transmission infrastructures - overhead power lines (OPL). The main objective of this work is to present the methodology of risk analysis of the EWEs on OPL in Portugal. The level of risk associated with each of the identified events is classified according to the probability of occurrence and consequences, in a risk matrix, and through the cause-and-effect analysis. It is concluded that, in Portugal, the extreme wind – corresponding to level 11 of the Beaufort Wind Force Scale, that is, values equal to or higher than 105.1 km h−1 (29.22 m s−1) – is the main factor that provoked the OPL disruption, between 28% and 40% of analyzed events associated with windstorms. Considering the occurrence of compound events - wind and rain - the probability of damage to OPL is between 21% and 30%; for wind and ice, it is 3%–5%. EWEs represent a serious risk for electrical systems, and it is necessary to develop effective solutions to minimize the associated impacts, such as the modification and upgrade of the current design and engineering standards, and electrical network monitoring. [Display omitted] • Extreme weather events have a wide impact on the overhead power lines. • Damage to electricity infrastructure has strongly affected consumers and the environment. • Risk analysis and management play a decisive role in adapting to extreme events. • Measures are proposed to minimize the disruption risk of the systems in Portugal. [ABSTRACT FROM AUTHOR]

Background Experimental studies suggest that nocebo responses might occur after exposure to equipment emitting electromagnetic fields such as high voltage power lines (HVPLs) or mobile phone base stations. Objectives The present study investigates to what extent health responses to a new HVPL can be explained by beliefs of residents regarding the health effects of HVPLs. Methods We used a quasi-experimental prospective field study design with two pretests during the construction of a new HVPL, and two posttests after it has been put into operation. Residents living near (0–300 m, n = 229; 300–500 m, n = 489) and farther away (500–2000 m, n = 536) filled out questionnaires about their health and their beliefs about the negative health effects of power lines. Longitudinal mediation models were applied to investigate to what extent these beliefs could explain a change in reported symptoms after the new line was put into operation. Results Significant (p < .01) indirect effects were found for proximity on the increase in reported cognitive (R 2 = 0.41) and somatic (R 2 = 0.79) symptoms after the power line was put into operation through an increase in the belief that power lines causes health effects. The direct effects of proximity on an increase in reported symptoms were not significant. Conclusions Our findings suggest that increases in reported health complaints after a new HVPL has been put into operation can be explained by nocebo mechanisms. Future field studies are needed to know whether our findings extend to other environmental health issues in a community. [ABSTRACT FROM AUTHOR]

In this study, we estimated the impact of different management strategies on the ecosystem services provided by the vegetation under electric power lines in urban and rural areas. Two management scenarios were evaluated in urban areas: (a) complete removal of trees that interfere with power lines, and (b) pruning of these trees. Four management scenarios were evaluated in rural areas, where power lines cut through wood lots and forests: (1) clear-cutting with whole-tree removal, (2) clear-cutting with slash left on site, (3) selective logging with slash left on site, and (4) tree pruning only. Because it was not feasible to carry out field experiments to examine the effects of all of these management scenarios on fourteen ecosystem services, we used the Delphi method to solicit expert opinion and address testable predictions and preliminary management recommendations. According to this expert survey, pruning is expected to have little or no effect on a range of services provided by trees, woodlands and forests either in rural or urban areas. On the other hand, all other scenarios are expected to have similar effects on at least half the services evaluated. Based on these results, we recommend that pruning be prioritized over other management practices as much as possible in urban and rural settings. [ABSTRACT FROM AUTHOR]

The use of indicator species may save a considerable amount of resources when the attributes of other species or of the ecological process of interest are difficult or costly to measure directly. However, identifying indicator species is not easy and there is a need for rigorous criteria and methods for their selection. In this study, we test a new approach to select indicator species of high mortality-risk of electrocution in power pylons comparing methods based on biological criteria and network analysis. For this purpose, we studied 335 mortality records of 19 bird species electrocuted between 1996 and 2013 in a Special Protected Area located in South-eastern Spain. Our results showed that both species-biology based methods and network analyses provided similar results, indicating that the eagle owl can be considered the best mortality indicator of the bird community on power pylons for the study area. The use of network analysis to select indicator species can be very useful to optimize the monitoring of infrastructure impacts, especially on complex or understudied communities because it does not require detailed information on the biology of the species. [ABSTRACT FROM AUTHOR]

This paper proposes application of wireless power transfer for charging of electric-powered Unmanned Air Vehicles (UAV)s. Multi-rotor systems, such as quadrotors, are light-weight and easy to operate. They are available in different sizes and with the wide range of capabilities. The main limitation of electric-powered UAVs is their range and endurance, due the limited battery capacity. Increasing battery system size is not a viable solution as its weight becomes a limiting factor. Supercapacitors are not an option, because of their low energy density. An alternative is to recharge UAV on the job, using wireless energy transfer (WET). WET was originally investigated by Nikola Tesla in the beginning of the 20 th century. His patents are now common ground for any power transmission technology research, both wired and wireless. Investigations in resonance-based wireless energy transfer promise efficient wireless power transmission over several meters. This offers an ability to recharge moving vehicles, such as cars, trains and UAVs, wirelessly. For example, this technology can be applied to extend the range of UAVs used for the inspection of power transmission lines and towers. Presented project investigate capabilities and limitations of the wireless power transmission, for particular UAV application, i.e. for the infrastructure inspections. [ABSTRACT FROM AUTHOR]

Corona ions produced by high-voltage power lines (HVPLs) can alter the nearby electrical environment, potentially increasing aerosol charge levels downwind. However, there is a lack of knowledge concerning the concentration and mobility of ions from AC HVPLs and their dispersion away from the line. We present ion concentration and mobility measurements made near AC HVPLs in South-West England. Examples of typical mobility spectra are shown highlighting features commonly observed. Corona was observed during 33 of 46 measurements, at 9 of 11 sites, with positive or 'bipolar' (both polarities) ion production commonly seen. Ion production usually increases atmospheric concentrations by only a modest amount, but extreme cases can enhance concentration by an order of magnitude or more. A polarity imbalance is required to increase aerosol charge via ion attachment; this was observed on 15 of 24 days when positive corona was observed, but was not seen for negative ions. Ion mobility was higher downwind compared with upwind for both ion polarities, but the increase was not statistically significant. Future work should focus on identifying and characterising 'heavy-producing' HVPLs, and obtaining results in conditions which may favour negative ion production e.g. high humidity, inclement weather or during nighttime. [ABSTRACT FROM AUTHOR]

Transmission lines located in the desert are subjected to desert climate, one of whose features is sandstorms. With long accumulation of sand and with the advent of moisture from rain, ambient humidity and dew, a conductive layer forms and the subsequent leakage current may lead to surface discharge, which may shorten the insulator life or lead to flashover thus interrupting the power supply. Strategically erected power lines in the Egyptian Sinai desert are typically subject to such a risk, where sandstorms are known to be common especially in the spring. In view of the very high cost of insulator cleaning operation, composite (silicon rubber) insulators are nominated to replace ceramic insulators on transmission lines in Sinai. This paper examines the flow of leakage current on sand-polluted composite insulators, which in turn enables a risk assessment of insulator failure. The study uses realistic data compiled and reported in an earlier research project about Sinai, which primarily included grain sizes of polluting sand as well as their salinity content. The paper also uses as a case study an ABB-designed composite insulator. A three-dimensional finite element technique is used to simulate the insulator and seek the potential and electric field distribution as well as the resulting leakage current flow on its polluted surface. A novel method is used to derive the probabilistic features of the insulator’s leakage current, which in turn enables a risk assessment of insulator failure. This study is expected to help in critically assessing – and thus justifying – the use of this type of insulators in Sinai and similar critical areas. [ABSTRACT FROM AUTHOR]

Abstract: Studies have suggested that residential exposure to extremely low frequency (50Hz) electromagnetic fields (ELF-EMF) from high voltage cables, overhead power lines, electricity substations or towers are associated with reduced birth weight and may be associated with adverse birth outcomes or even miscarriages. We previously conducted a study of 140,356 singleton live births between 2004 and 2008 in Northwest England, which suggested that close residential proximity (≤50m) to ELF-EMF sources was associated with reduced average birth weight of 212g (95%CI: −395 to −29g) but not with statistically significant increased risks for other adverse perinatal outcomes. However, the cohort was limited by missing data for most potentially confounding variables including maternal smoking during pregnancy, which was only available for a small subgroup, while also residual confounding could not be excluded. This study, using the same cohort, was conducted to minimize the effects of these problems using multiple imputation to address missing data and propensity score matching to minimize residual confounding. Missing data were imputed using multiple imputation using chained equations to generate five datasets. For each dataset 115 exposed women (residing ≤50m from a residential ELF-EMF source) were propensity score matched to 1150 unexposed women. After doubly robust confounder adjustment, close proximity to a residential ELF-EMF source remained associated with a reduction in birth weight of −116g (95% confidence interval: −224:−7g). No effect was found for proximity ≤100m compared to women living further away. These results indicate that although the effect size was about half of the effect previously reported, close maternal residential proximity to sources of ELF-EMF remained associated with suboptimal fetal growth. [Copyright &y& Elsevier]

Highlights: [•] Interviewees believe that landscape is an economic resource for Italy. [•] 39% of the sample is not willing to pay for the burial of power lines. [•] More than 50% of the sample is in favour of a burial policy. [•] The burial finds an economic justification only in areas of relevant environmental interest. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2006.01.005 Byline: V.C. Gungor (a), F.C. Lambert (b) Keywords: Electric system automation; Internet based Virtual Private Network; Power line communication; Satellite communication; Wireless sensor networks; Wireless mesh networks; WiMAX Abstract: In today's competitive electric utility marketplace, reliable and real-time information become the key factor for reliable delivery of power to the end-users, profitability of the electric utility and customer satisfaction. The operational and commercial demands of electric utilities require a high-performance data communication network that supports both existing functionalities and future operational requirements. In this respect, since such a communication network constitutes the core of the electric system automation applications, the design of a cost-effective and reliable network architecture is crucial. In this paper, the opportunities and challenges of a hybrid network architecture are discussed for electric system automation. More specifically, Internet based Virtual Private Networks, power line communications, satellite communications and wireless communications (wireless sensor networks, WiMAX and wireless mesh networks) are described in detail. The motivation of this paper is to provide a better understanding of the hybrid network architecture that can provide heterogeneous electric system automation application requirements. In this regard, our aim is to present a structured framework for electric utilities who plan to utilize new communication technologies for automation and hence, to make the decision-making process more effective and direct. Author Affiliation: (a) Broadband and Wireless Networking Laboratory, School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States (b) National Electric Energy Testing, Research and Applications Center, Georgia Institute of Technology, Atlanta, GA 30332, United States Article History: Received 18 January 2006; Accepted 26 January 2006 Article Note: (miscellaneous) Responsible Editor: I.F. Akyildiz

Power lines foreign object detection task is to detect objects suspending on power lines, they might be kites, plastic bags or anything else, which could be a potential risk to power system. However, this task remains a challenge due to the lack of data, because these data can only be produced by a few major video surveillance companies, who treat their data as valuable property and will not share it with others. Without massive training data, we could not obtain an excellent neural network. In this paper, we introduce a new data composition method to generate artificial data and help alleviate the data shortage problem. What is more, we propose a new detection method called Edge Proposal Network (EpNet) to reduce wrong proposal locations and increase detection performance. At last, we conduct several experiments to verify the effectiveness of the two methods, and some discussion experiments to gain a deeper understanding of the composited data. [ABSTRACT FROM AUTHOR]

• A vision-based method which allows safe, low-cost and accurate sag measurement for power lines. • Sag inspection remotely based on a single shot taken by a smartphone. • Space resection of perspective images in the ill-posed condition and weak geometry of control data. • Plumb lines determination in perspective images. • Integration of smartphone sensors' data for photogrammetric solutions. • The usage of smartphone's accelerometer data to facilitate the attitude determination of its captured images. Measuring the sag of electrical power transmission cables is an index for sensing their internal tension and safety. In this paper, a simple photogrammetric solution is proposed to measure them which only requires an image taken by a smartphone equipped with an internal accelerometer. In this method, a modified version of the well-known co-linearity condition is proposed and the 3D locus of cables has been modeled with a parabola equation. Accelerometer measurements are used to prevent the ill-posed conditions of unknowns' estimation and are also contributed to generating the control data for the estimation of unknowns. The distance between the supporting points of cables is the only required control information for this method. The proposed solution, while simple, significantly has reduced the risks and costs of measuring the cable sags. On average, the obtained results indicate a relative accuracy of 2.6% in the estimation of the sags of cables. [ABSTRACT FROM AUTHOR]

Abstract: There is a natural potential gradient caused by global thunderstorm activity that can be measured from the ground using electric field mill meters. High voltage power lines can produce corona ions by ionising the air, depending on the ambient weather conditions. A fixed site monitoring station recorded atmospheric potential gradient and weather conditions near to two AC high voltage power lines throughout 2008. High humidity correlated with negative potential gradient both upwind and downwind of power lines and high wind speed correlated with greater potential gradient disruption. Rain caused the greatest disruption to potential gradient, causing negative fields and an increased standard deviation. Multiple regression analysis also showed that humidity and wind speed have an effect on the production of corona ions and quantile regression plots indicate a clear trend of decreasing mean potential gradient with increasing wind speed and relative humidity. [Copyright &y& Elsevier]

Abstract: Simultaneous ion concentration and potential gradient measurements were made at AC high voltage power lines using ion mobility spectrometers and electric field mills. A significant (p < 0.01) change in central tendency and variability of ion concentration and potential gradient can occur downwind of power lines. In 3 out of 8 downwind measurements, there was a discrepancy of sign between the overall mean of these quantities, attributed to ion dispersion and ion–aerosol attachment. While ion concentrations give a greater indication of personal exposure, potential gradient measurements are more appropriate for assessment of the behaviour of a power line. [Copyright &y& Elsevier]

Abstract: In 2002, the International Agency for Research on Cancer (IARC, 2002) categorized extremely low frequency (ELF) (including the power frequencies of 50 and 60Hz) magnetic fields as “possibly carcinogenic to humans.” That was based on pooled analyses of epidemiological research that reported an association between exposure to low-level magnetic fields and childhood leukemia. In 2007 a task group of scientific experts convened by the World Health Organization (WHO) acknowledged the IARC categorization but found that the laboratory studies and other research results did not support the association. Taking all evidence into account WHO reported that it could not confirm the existence of any health consequences from exposure to low-level magnetic fields. There remains continuing concern by some people that exposure to power frequency magnetic fields may cause adverse health effects, particularly childhood leukemia. Public health authorities need to fully understand the reasons for that ongoing concern and effective ways to address it. This paper describes what drives the concern, including how people perceive risks, how WHO and other public health authorities assess scientific research to determine whether health risks exist and the conclusions they have reached about power frequency magnetic fields. This paper also addresses the scientific basis of international exposure guidelines for power frequency magnetic fields and what precautionary measures are warranted to address the concern. [Copyright &y& Elsevier]

Abstract: The Earth''s background potential gradient (PG) has a diurnal cycle (the ‘Carnegie curve’) that can be exhibited in fair weather when there are no local sources of space charge. High voltage power lines can create corona ions which are released into the atmosphere and can disrupt the natural PG. A fixed site monitoring station measured the vertical potential gradient at 1s intervals alongside local weather conditions to investigate the time of day at which corona production is greatest downwind of a power line. In upwind conditions, the average PG curve returned correlates well with the Carnegie curve, but this is masked under downwind conditions. Overnight, the PG downwind of the monitoring station is more variable and more negative than upwind. Downwind of the power line there is significantly more variability of potential gradient after sunrise and before sunset on most days. [Copyright &y& Elsevier]

Abstract: There is an ongoing scientific controversy whether the observed association between exposure to residential extremely low-frequency magnetic fields (ELF-MF) and the risk of childhood leukaemia observed in epidemiological studies is causal or due to methodological shortcomings of those studies. Recent pooled analysis confirm results from previous studies, namely an approximately two-fold risk increase at ELF-MF exposures ≥0.4 μT, and demonstrate consistency of studies across countries, with different design, different methods of exposure assessment, and different systems of power transmission and distribution. On the other hand, recent pooled analyses for childhood brain tumour show little evidence for an association with ELF-MF, also at exposures ≥0.4 μT. Overall, the assessment that ELF-MF are a possible carcinogen and may cause childhood leukaemia remains valid. Ongoing research activities, mainly experimental and few new epidemiological studies, hopefully provide additional insight to bring clarity to a research area that has remained inconclusive. [Copyright &y& Elsevier]

Abstract: Over the past several decades, concerns have been raised over the possibility that the exposure to extremely low frequency electromagnetic fields from power lines may have harmful effects on human and living organisms. This work involved the computation of the magnetic field generated by 110kV overhead power lines using a normalized radial basis function (NRBF) network. Training of the evolving NRBF network is achieved by using the data generated from the numerical simulation based on Charge Simulation method (CSM). Then, NRBF has been used to determine the magnetic field distribution in a new geometry differing from the geometries used for training. These test results show that proposed NRBF network can be used as useful tool to calculate the magnetic fields from power lines, alternative to the conventional methods. [Copyright &y& Elsevier]

Abstract: Positive and negative small ions, aerosol ion and number concentration and dc electric fields were monitored at an overhead high-voltage power line site. We show that the emission of corona ions was not spatially uniform along the lines and occurred from discrete components such as a particular set of spacers. Maximum ion concentrations and atmospheric dc electric fields were observed at a point 20 m downwind of the lines. It was estimated that less than 7% of the total number of aerosol particles was charged. The electrical parameters decreased steadily with further downwind distance but remained significantly higher than background. [Copyright &y& Elsevier]

Abstract: As an initial electric fault occurs, the fault current would result in a strong magnetic force and torque exerted on the power line conductors. The rotational magnetic torque, in turn, would make the power lines with sags swing and may bring them to close proximity or in contact with one another, causing a subsequent fault. For the analysis of the magnetically induced subsequent fault (MISFault), software has been developed as the end product of a multi-year research project sponsored by Duke Energy Company. The software is capable of predicting the smallest distance between the power line conductors during their swing procedure, from which one can predict the probability of the magnetically induced subsequent fault; and determine the allowed span length range from consideration of eliminating the subsequent fault, which is anticipated to be useful for a utility in long span design. The software has been tested and the accuracy of its computation results has been validated by verifying that the energy conservation law requirement is well satisfied. The MISFault software is being used by Duke Energy Company. It is user friendly and is expected to be useful to a utility for eliminating the magnetically induced subsequent fault. [Copyright &y& Elsevier]

Abstract: Single Wire Earth Return (SWER) systems are used for supplying electricity at low cost, where electricity supply is required for small populations of people dispersed across wide geographical areas. It is principally used for rural electrification, but is also used for other isolated loads and light rail. The existing SWER distribution systems have been stretched with the sharp growth of their loads because of customers’ change of lifestyle, which has introduced additional load of air conditioning equipment, motors driven by variable-speed drives and inverters. This paper proposes cost-effective solutions to address the problem of voltage regulation and compensation of the unbalancing effect of SWER lines on the three-phase feeder of these lines, which have been exacerbated by this load growth. To improve the voltage regulation problem, a LV switchable reactor has been designed, a prototype made and tested in the field. Also, an unbalance compensator has been designed to reduce the unbalancing effect of SWER lines. Two case networks have been used to perform simulation studies on the effectiveness of both proposed solutions. At first, a case study is used to demonstrate the impact of a switchable reactor on improving voltage regulation. Then, another case study shows that installation of a switchable reactor and an unbalance compensator simultaneously on a SWER distribution system effectively improves voltage regulation and reduces unbalancing effects. [ABSTRACT FROM AUTHOR]

Abstract: High voltage power lines are known to produce corona ions that can be carried from the line by the wind, progressively attaching to ambient aerosol particles and causing fluctuations in the Earth’s atmospheric potential gradient. A fixed site monitoring station was installed near two power lines, which recorded the potential gradient at 1s intervals and the ambient weather conditions every 10min. The station ran continuously from January 2007 to December 2008, accumulating long-term data. Results from 2008 show an increase in potential gradient variability when a wind is blowing across the power lines towards the station, indicating that corona ions may be present in this environment. [ABSTRACT FROM AUTHOR]

Abstract: A wet snow event in the northwest part of Germany caused extensive damage to electric power lines in November 2005. Maximum wet snow loads of approximately 50Nm− 1 were estimated by evaluating the snow deposit diameter from photographs and the snow density from meteorological data. A simple wet snow accretion model was applied to reconstruct the snow accretion process. The maximum wet snow loads estimated by the model are in good agreement with the observations when the model input parameter, visibility, was adjusted by a constant factor for night-time observations. The improved wet snow accretion model was also applied to historical weather data for the area demonstrating the power and weaknesses of the extreme value analysis of wet snow events. [Copyright &y& Elsevier]

Abstract: Over the past several decades, concerns have been raised over the possibility that the exposure to extremely low frequency electromagnetic fields from power lines may have harmful effects on human and living organisms. This paper presents novel approach based on the use of both feedforward neural network (FNN) and adaptive network-based fuzzy inference system (ANFIS) to estimate electric and magnetic fields around an overhead power transmission lines. An FNN and ANFIS used to simulate this problem were trained using the results derived from the previous research. It is shown that proposed approach ensures satisfactory accuracy and can be a very efficient tool and useful alternative for such investigations. [Copyright &y& Elsevier]

Abstract: Nesting on high voltage transmission line towers exposes birds to electric and magnetic fields for long periods. Nestlings are exposed from their development in ovo until fledging. This is a critical period for them because the quality of the developmental environment may affect their fitness at adulthood. We carried out a field study on Eurasian kestrels, Falco tinnunculus, to compare chicks from pairs nesting on high voltage power lines vs. those nesting in control sites in similar habitats. The magnetic field (MF) was measured in each nest-box and analysed in relation to growth curves, melatonin levels, leukocyte counts, and fledging success. None of the variables differed between exposed and control nestlings. Wing length (proxy of age) showed a negative covariation with serum melatonin concentration. Our findings suggest that exposure to MFs produced by high voltage power lines during the embryonic and post-hatching period (until fledging) does not have significant short-term physiological effects on kestrel nestlings. [Copyright &y& Elsevier]

Abstract: An initial electric fault can result in strong magnetic torque exerted on overhead power line conductors, which will make them swing and may bring them to close proximity or in contact with one another, causing a subsequent fault. Computer simulations have been developed for the analysis of the subsequent fault and presented in the authors’ earlier work for level spans and inclined spans that are both of uniform power line construction. However, in practice, a power line topology may require a transition from one power line structure to another. Such a required transition can be realized by a transition span. In this paper, we present a dynamic analysis of swing movement of power line conductors in a transition span subsequent to an initial fault, to track the smallest distance between the conductors, which is an important factor useful for predicting the probability of the subsequent fault. The analysis is much more complex than that for level spans and inclined spans. To address the complexity, we employ coordinate system transformations and establish a common coordinate system, then make use of it in the dynamic analysis. Sample numerical results are presented, analyzed, and checked with the energy conservation law requirement. [Copyright &y& Elsevier]

This paper reports net concentrations of small ions (NCSI) monitored at 41 sites under overhead high voltage ac power lines in and around an urban environment. The net ionic polarity under power lines was of both signs but mostly positive and NCSI varied widely from 0 to 3300cm−3. Concomitant measurements of the vertical dc electric field at the ground confirmed the presence of a net positive charge above. Approximately, 19% of the sites exhibited relatively high NCSI exceeding 1000cm−3. The mean value of all the sites was 776cm−3. Statistically, the mean for the transmission voltage (220–330kV) line sites was significantly higher than that for the sub-transmission voltage (110–132kV) line sites with means of 905 and 501cm−3, respectively. These values were compared with the mean urban outdoor concentration well away from the lines which was about 400cm−3 and of negative polarity. Overall, NCSI at approximately 76% of the power line sites exceeded the absolute mean urban outdoor value. The dc electric fields under the power lines showed a statistically significant relationship to the measured NCSI, although there was considerable scatter to indicate that electric field measurements do not necessarily reflect NCSI in the air at ground level. [Copyright &y& Elsevier]

We systematically reviewed the raptor electrocution literature to evaluate study designs and methods used in raptor electrocution research, mitigation, and monitoring, emphasizing original research published in English. Specifically, we wondered if three decades of effort to reduce raptor electrocutions has had positive effects. The majority of literature examined came from North America, western Europe, and South Africa. In spite of intensive and often sustained effort by industry and governments across three continents for 30 years, reductions in the incidence of electrocution have been demonstrated in only a few studies. Reliable rate estimates of electrocution mortality generally are unavailable, with some exceptions. Nearly half of 110 studies we analyzed in detail were retrospective reviews of historical mortality records, banding data, or results of necropsies on dead birds received at pathology and veterinary facilities. Among prospective studies, less than half used unbiased approaches to sampling and many did not provide enough detail to assess the sampling design used. At this time, few researchers can demonstrate the reliability of standardized retrofitting procedures or the effectiveness of monitoring techniques. Future progress in reducing raptor mortalities on power lines will benefit from properly designed studies that generate rate estimates of mortality, address biasing factors, and include predictions concerning risk and techniques to reduce risk that can be tested in the field or laboratory. [Copyright &y& Elsevier]

This survey estimated the extremely-low-frequency magnetic field (ELF-MF) exposure in households with children under the age of 7 years in Taiwan. To select a representative sample, we used the probability proportional to size sampling technique and simple random cluster sampling technique to select study districts in each city/county of Taiwan. A total of 40 districts were selected and all households with children aged less than 7 (n =4184) were visited and solicited for in-home measurements. Four trained interviewers carried out spot-measurements in rooms of each selected household during a two-year period. A questionnaire inquiring residential characteristics and nearby power facilities was also administered to a parent or caregiver. ELF-MF measurements were performed in a total of 2214 households (53% participation rate). Controlling for participation rate, the weighted overall mean magnetic field exposure was estimated at 0.121 (standard deviation 0.185) micro-Tesla (μT) (range 0.010–3.304 μT). Mean exposures were higher than 0.3 and 0.4 μT in an estimated 7.3% (n =159) and 5.4% (n =115) of the households, respectively. There was a substantial agreement between overall mean residential exposure and exposure measured in children''s bedrooms. In a multivariate logistic regression model, we noted that buildings with advanced age, buildings for both residential and commercial uses, and buildings close to power facilities were more likely a to have mean exposure above 0.4 μT. Our survey results indicate that residential ELF-MF exposure is likely to be higher for children in Taiwan than for children in Europe and North America. [Copyright &y& Elsevier]

Abstract: Linear infrastructures such as roads, pipelines and power lines can hinder Rangifer migration and reduce the total amount of area available for foraging. We studied the barrier and aversion effect of a 66kV power line transecting the range of wild reindeer in North Ottadalen, south central Norway using aerial surveys of reindeer distribution (direct measurement of reindeer use) and lichen measurements (indirect measurement of reindeer use) at varying distances from both sides of the power line. We present a clear definition of the expected barrier and aversion effects, and present specific hypotheses and predictions based on these two terms that are often used unclearly in the literature. The aerial surveys and ground observations showed that reindeer crossed underneath and grazed under and on both sides of the power line during 14 out of the 22years (63.6%) surveys were conducted over the last 31years. This behaviour was confirmed by the lichen measurements, indicating a higher use of lichen pastures along ridges close to and under the power line compared to those at increasing distances and up to 3km from both sides of the power line. This winter grazing pattern probably reflects the topographical channeling of reindeer to the ridges along an 8km wide topographical corridor encompassing the power line and cannot be attributed to the power line itself. We found that direct measurement data (visual observations such as ours or GPS/telemetry tracking) provide less ambiguous information for testing barrier and aversion effects than indirect measurement data (pasture/lichen measurements) that are likely influenced by numerous uncontrollable environmental variables independent of reindeer grazing. Our results contrast with recent studies indicating strong barrier and aversion effects of similar power lines for Rangifer migration and grazing behaviour in alpine terrain. [Copyright &y& Elsevier]

Abstract: The extreme events that are likely to occur for poles and towers of power transmission lines during severe wind and ice storms are discussed. Extreme wind storm, ice deposit and broken conductor events and relevant loads of structures are considered. The structural performance of prestressed spun (centrifugally cast) concrete poles of annular cross-section and metal towers are analysed. The time-dependent performance processes of particular members (sections or angle bars) are presented in terms of their random safety margin sequences. The survival probability of poles and towers as autosystems representing their multicriteria failure mode is analysed. It is recommended that their survival probabilities are calculated using the analytical method of transformed conditional probabilities. The target reliability index of poles and towers is considered. [Copyright &y& Elsevier]

Abstract: The Environmental Impact Assessment (EIA) process concerning the route of a 400 kV power transmission line between Loviisa and Hikiä in southern Finland was reviewed in order to assess how biodiversity issues are treated and to provide suggestions on how to improve the effectiveness of treatment of biodiversity issues in impact assessment of linear development projects. The review covered the whole assessment process, including interviews of stakeholders, participation in the interest group meetings and review of all documents from the project. The baseline studies and assessment of direct impacts in the case study were detailed but the documentation, both the assessment programme and the assessment report, only gave a partial picture of the assessment process. All existing information, baseline survey and assessment methods should be addressed in the scoping phase in order to promote interaction between all stakeholders. In contrast to the assessment of the direct effects, which first emphasized impacts on the nationally important and protected flying squirrel but later expanded to deal with the assessment of impacts on ecologically important sites, the indirect and cumulative impacts of the power line were poorly addressed. The public was given the opportunity to become involved in the EIA process. However, they were more concerned with impacts on their properties and less so on biodiversity and species protection issues. This suggests that the public needs to become more informed about locally important features of biodiversity. [Copyright &y& Elsevier]

Abstract: The experimental study of the influence of HV AC 400 and 110kV (rms) power lines on the concentration of the intermediate and light large air ions, was carried out for potential health effects evaluation. The measurements were done with the modified aspiration ion counter, 0.5m above the ground. It was found that up to 100m on the leeward side of the line the density of positive charge carried by medium and large ions was higher up to 3.9-fold than on the windward side and negative charge up to 2.2-fold with the excess of positive ions. Between 100 and 300m, the concentration of negative ions became higher than that of positive ones. [Copyright &y& Elsevier]

The increasing complexity of transmission networks can raise significantly the load flows during and following serious system disturbances. In this context accurate thermal rating assessment of overhead lines represents an essential requirement in order to obtain a sensible increase of the infrastructure exploitation assuring at the same time a reliable functioning of the power networks.This necessitates reliable calculation models which should be able to predict the thermal behaviour on short and long time horizons and in the presence of data uncertainties deriving from several sources such as non stationary load and fluctuating operating conditions.To address this problem, in the paper the use of Affine Arithmetic, an enhanced model for numerical computation, is proposed. Using AA, the thermal rating solution is computed taking into account the model parameter uncertainty interdependencies as well as the diversity of uncertainty sources.Simulation studies are presented and discussed in order to prove the effectiveness of the proposed methodology in addressing the problem of uncertainty analysis in both static and dynamic thermal rating assessment. [Copyright &y& Elsevier]

As an electric fault occurs, a strong magnetic force exerted on three-phase overhead power lines may bring them in close proximity or in contact with one another, causing a subsequent fault. A computer simulation has been developed for the analysis of the magnetically induced subsequent fault and presented in the authors’ earlier work. It has been found that one important factor affecting the probability of the subsequent fault is the power line configurations. In this paper, we present a numerical technique for determining the maximum span length of the power lines based on consideration of eliminating the magnetically induced subsequent fault. Various power line constructions corresponding to different fault current levels are investigated. The results presented in this paper are anticipated to be useful for a utility in long span design. [Copyright &y& Elsevier]

As an electric fault occurs, a strong magnetic force and torque exerted on three-phase overhead power line conductors would make them to swing and may bring them to close proximity or in contact with one another, causing a subsequent fault. A computer simulation has been developed for the analysis of the magnetically induced subsequent fault and presented in the authors’ earlier work, for level spans. However, the power line construction in mountainous areas requires the use of inclined spans. In this paper, we present an analysis of the magnetically induced subsequent fault in inclined-span utility line topologies. This analysis is in a transformed coordinate system, making use of electromagnetic theory and fundamental laws of mechanics as well as numerical methods. Power lines with different inclined angles are studied and the numerical results are compared with that for level spans. To validate the accuracy of the numerical results, they are checked with the energy conservation law requirement. [Copyright &y& Elsevier]

We made monthly surveys of >2000 reindeer (Rangifer tarandus tarandus) from 1977 to 1987 before and after the construction of the Blue Lake hydroelectric reservoir in order to study the progressive impact of infrastructure development on wildlife. Following this development, reindeer densities within a 4-km radius declined gradually during winter to 8% of pre-development densities without significant changes in undeveloped control sites. During summer, reindeer gradually reduced use of areas within 4 km distance from roads and power lines to 36% of predevelopment density, with subsequent 217% increase in use of the few remaining sites located >4 km from infrastructure. Reindeer reproduction declined progressively as habitat was lost. Assessments of individual development projects seriously underestimate the long-term effects of the entire expanding infrastructure network. Piecemeal development has resulted in an estimated 70% loss of undisturbed reindeer habitat across the last century in Norway. During this time the reindeer population has become fragmented into 26 isolated sub-populations. Our results show that any further infrastructure development will put the remaining European population of wild mountain reindeer at great risk, as further habitat fragmentation will make the remaining undisturbed patches too small for holding viable populations. A general model of impacts of infrastructure on wildlife is presented. We discuss the importance of controlling piecemeal development in infrastructure for conservation of wildlife and argue that minimizing infrastructure development is likely one of the largest challenges in wildlife conservation ahead. [Copyright &y& Elsevier]

The failure of the conductor of the 460 kV overhead transmission line located along the crossing of the Parana´ River was investigated. As a result of this failure, a blackout took place in the southern states of Brazil in January of 2002, reaching approximately 67 million inhabitants. Investigation of the external aluminium layer of the ACSR conductor near the fracture showed typical static deformation marks and dynamic fretting wear tangential marks, both associated with the presence of Al2O3 debris. Additionally, encrusted silicon particles were observed on the external surface of the strands. The internal Al layer showed elliptical deformation marks also associated with Al2O3 debris. Both Al2O3 and Si particles are efficient abrasive material, which associated with slight relative motion of metallic surfaces (clamp/strand and strand/strand) can promote fretting wear. Two types of fracture surface of the Al strands were identified: 45° and quasi-normal surfaces, the former being the predominant type. Delamination and particle detachment were the mechanisms of superficial degradation observed on the Al strands, indicating that the rupture of the strands occurred under a gross slip fretting regime induced by sub-conductor oscillation. Inspection of the internal surface of as-cast Al–10%Si spacer clamps revealed different stages of intense circumferential wear caused by the preferential cracking and particle detachment of the eutectic constituent of the as-cast microstructure. This intense wear reduces the clamping contact pressure, which allows higher displacement amplitude and leads to the critical fretting regime. Finally, a few suggestions are discussed to minimise the occurrence of future failures. [Copyright &y& Elsevier]