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• The lifetime of PV power plants does not reach the expected 20–25 years. • Data monitoring from 85 PV power plants in central Europe is used. • The real lifetime of PV power plants is about half the planned time. After 10 years of operation the frequency of serious failures rises sharply. • The examples of delamination, the formation of a conductive channel between the electrode and the grounded frame of the PV panels are demonstrated, the number of damaged inverters is analysed. • To calculate the economic efficiency of investments in PV power plants, the methods: payback period (PP), net present value (NPV), and internal rate of return (IRR) were used. The maintenance and analyzing failures of PV systems and plants are becoming more and more important issues. Our data from the long-term operation of 85 photovoltaic power plants in central Europe show that their actual lifetime is about half that of the originally planned lifetime. After about 10 years, serious failures of 1st tier (bankable) PV panels occur at an increasing rate. This article presents selected typical data and describes the most serious failures. Furthermore, economic calculations of returns on investment are carried out in relation to the price of electricity, which is currently changing at a rapid pace. It shows that the PV panel lifetime reduction from 20 to 30 years, declared at commercial leaflets, to real lifetime about 10–12 years can reduce PV power plant profit substantially, but the investment is still worth it. The reason is that after 10–12 years ser vice/maintenance expenses to replace damaged PV panels and inverters are growing very quickly. The new information could be helpful for owners of PV power plants to get a more realistic estimation of profits. [ABSTRACT FROM AUTHOR]

• There is still an unmet medical need for new therapies to treat idiopathic pulmonary fibrosis (IPF). • The two approved drugs, nintedanib and pirfenidone, have significant issues with tolerability, safety and, efficacy. • Several drug candidates have been studied in Phase 2b or 3 trials, with most programs failing and no approvals to date. • Analysis of these failures offers novel paradigms for new approaches to overcome the barriers to success. Idiopathic pulmonary fibrosis (IPF) is an area of high unmet clinical need and high research activity in the pharmaceutical and biotech industries. The two approved therapies, nintedanib and pirfenidone, have issues with efficacy and tolerability. Despite a considerable number of development programs reaching late-stage Phase 2b or 3 clinical trials, no drug other than nintedanib and pirfenidone has successfully demonstrated a benefit for patients. An analysis of these failures, and consideration of the trajectories of some of the current development projects, may offer novel paradigms for choosing modes-of-action and for the development of successful drugs. [ABSTRACT FROM AUTHOR]

• The manuscript presents failures observed on voltage transformers (VTs) and CTs that operate at 150 kV and 400 kV, based on statistical data from real operating networks. • Following failure analysis, it is concluded that the percentage of failures for the VTs over the total installed parts on the 150 kV electricity network is higher than that for the CTs. • Even the number of failures for the VTs is larger than the corresponding number for CTs, the statistics show that finally the CTs present considerably less lifetime than the VTs. Electric power infrastructures are considered to be the most critical. The required monitoring of electricity networks is achieved using instrument transformers. The instrument transformer operating conditions must be kept steady, within safe limits. However, this entails comprehension of the several reasons that lead to failure. These reasons can introduce condition assessment monitoring techniques aiming to protect this type of electrical equipment and maybe contribute on their predictive maintenance. This paper describes the probable failures in high voltage instrument transformers with operating voltages of 150 kV and 400 kV, the rate and trend of failures as well as their basic sources. More specifically, this research has been applied for the 150 kV and 400 kV instrument transformers that are installed at the Hellenic Electricity Transmission Network. The results of this work will provide valuable insights about failure cause and operational life of measuring transformers in transmission networks allowing them to improve monitoring and resilience of the networks. [ABSTRACT FROM AUTHOR]

To gauge the potential effect of mode of content delivery on overall student success in a pharmaceutical sciences course in a doctor of pharmacy program. Principles of Drug Action I (PDAI) is a first-year pharmaceutical science course typically taught by multiple faculty, and each utilizes their own approach to deliver course content. Over a seven year period, the course naturally separated into blocks. Block-1 was taught using a traditional lecture-based approach while Block-2 varied between either a lecture-based or a flipped-classroom format. Student success was evaluated by exam at the end of each block. For the four years in which Block-2 was taught by lecture, the number of exam failures was similar to Block-1. For each of the three years Block-2 was taught via the flipped-classroom format, the number of exam failures was approximately half that of Block-1. While grades for the lecture-based Block-1 trended downward over the seven-year evaluation period, average exam grades overall were similar between Block-1 and Block-2 each year regardless of teaching modality. Retrospective analysis of this novel blocked approach within PDAI provided a means of internally evaluating the potential effect of teaching format on overall student performance. The results described here support previous studies that indicate that the flipped-classroom approach can reduce course failures. These findings also show that flipped-classroom teaching may have a greater impact on improving learning in lower-performing students. [ABSTRACT FROM AUTHOR]

In Pakistan, the enormous 2010 floods inflicted unprecedented destruction to 0.5 million houses in South Punjab. This study was conducted in Muzaffargarh, a district of the Punjab province of Pakistan, one of the worst affected areas during the 2010 floods. As an adaptation and disaster risk reduction measure, an International NGO in collaboration with the Government of the Punjab province constructed 1274 houses for flood-affected communities. The houses were allocated through a lottery method. Initially, the allottees moved to the new settlements for the sake of possession. However, over time, it was observed that many flood-affected individuals sold out or rented their houses and returned to their villages/settlements. This qualitative study was conducted to identify the factors affecting the flood survivors' decision to return to their original villages/settlements after a certain time. The specific objective of the study was to identify the factors that pushed and pulled the flood survivors into their original settlements. The current study interviewed 20 respondents through the snowball sampling technique by using an interview guide. The findings highlighted the loss of social capital, place attachment, unavailability of grazing places, non-transfer of house, and increase in the cost of living were the major factors that pushed the flood survivors to return to their native villages. The current study highlighted social and psychological costs (such as nostalgia, homesickness, loss of social networks, etc.) for the relocation of disaster survivors. This study contains important policy implications regarding relocation decisions taken by the government and policymakers. Findings indicate relocation decisions as the failure to address the local needs, priorities, and contexts. [ABSTRACT FROM AUTHOR]

• Failure of antibiotics drug discovery and unmet need. • In antibiotics discovery it is mandatory to demonstrate the mechanism of action. • A distinctive property of an antibiotic is its bacteriostatic or bactericidal nature. • Vulnerability is the degree of inhibition of a target causing the necessary impact. Despite the unprecedented unmet need to discover new antibiotics, only a few molecules have been registered for clinical use. This shortage is primarily based on the scientific failure in the postgenomic era of drug discovery. It appears counterintuitive that knowledge of the bacterial genome was followed by the failure to produce new antibiotics using the paradigm of target-driven drug discovery. Here, I discuss the causes of the failures and also describe how small biotech is mitigating these risks and moving forward using new strategies to identify new antibiotics. [ABSTRACT FROM AUTHOR]

• We investigated the interposition of a stem taper adapter in terms of tribological interactions. • Investigations on wear, roughness, and corrosion on explants were conducted. • A higher incidence of second revisions on femoral head was noticed in absence of an adapter. • The surface analysis shows no predominant roughness values along any of the stem directions. • A homogeneous worsening or corrosion of the stem taper along the circumference was noticed. As revision surgeries of total hip arthroplasty are going to increase, success or failure of revised implants is a fundamental aspect in the orthopaedic field. Today, slight is known about the success rate of revised total hip arthroplasty when the femoral head is substituted on a retained stem. We wanted to investigate if the interposition of a stem taper adapter between the paired elements can influence this rate of success. From a total of more than 1000 revised implants, recorded during their follow up in a regional registry, the study was limited to the ones subjected to a surgical revision, where the head has been revised but the stem taper has not. Investigations on wear, roughness, and corrosion on the available explants were conducted, with the aim of providing visual and empirical response on the topic and to furnish to other researches useful data for comparison. Our results highlighted a higher incidence of second revisions when the femoral head is substituted without using an adapter. The topographic analysis refers that it is not evident a predominant roughness along any of the stems directions: no evidences were found that would define a recurrent rougher direction. This indicates a homogeneous worsening or corrosion of the stem taper along the circumference. Further, we found that the roughness values of the specimens analyzed not influence their surfaces and there is no a direct relation between the roughness of the bore heads and the stem tapers. [ABSTRACT FROM AUTHOR]

• The paper examines the institutional obstacles in Ghana. • Examine the transitional path of serial entrepreneurs after business failure. • Informal and formal entrepreneurship in Africa are examined. • Government policy and changes in government in Ghana are examined. • Entrepreneurial development in Ghana is examined. This study builds on prior scholarly works on institutions and entrepreneurship by examining the process of transitions and institutional obstacles that force serial entrepreneurs' shift to operate in the formal or informal sector after entrepreneurial business failures. Using insights from 32 serial entrepreneurs in Ghana, a framework was developed and utilized to explicate how the pull and push motivations for the transition into or persisting with formality or informality after business failure unfolds over time. Our analysis sheds light on the processes and effects of the motivations on the persistently high level of entrepreneurial activities in the informal sector for many emerging economies. [ABSTRACT FROM AUTHOR]

This paper studies the Cucker–Smale (C–S) flocking subject to random failure under general interaction topologies, which contain the hierarchical leadership and rooted leadership as special cases. Furthermore, at each time step, each of the agents can fail to interact with any of its neighbors. The random failures are assumed to be not independent. We prove that the flocking would occur almost surely under some conditions on the initial state of the flock only. The result suggests that the C–S flocking system on general digraphs can endure random failure in interactions. Finally, several numerical simulations are provided to illustrate the obtained results. [ABSTRACT FROM AUTHOR]

Highlights • The influence of grounding system in overhead lines failure. • New simulation-based EMTP was developed for sensibility analysis in grounding systems. • A recommendation for national and international standard for limit values for grounding system was proposed. [ABSTRACT FROM AUTHOR]

Product development (PD) faces uncertainties caused by rapidly developing technologies, shifting market demands and the changes occasioned by these developments, including new requirements for products being developed and increased difficulty for companies to reliably execute state-of-the-art processes. In this paper, we argue that classic PD risk management methods and tools are based on the 'predict and plan' paradigm, which assumes that organisation members involved in PD have sufficient time and resources to identify, analyse and mitigating technology risks and organisational risks. However, the reality of product development is that time and resources are rarely sufficient, and uncertainty is currently being introduced to the development process at an accelerated rate by trends such as pervasive digitalisation. This paper therefore investigates a resilience-inspired approach to PD risk management that abandons the predict and plan paradigm in favour of a 'monitor and adapt' approach. We argue that, in industrial practice, predict and plan approach is the de facto risk management baseline, and suggest deliberately tailoring risk management and PD processes to incorporate resilience-based practices. To that end, we provide suggestions for process frameworks and tools organisations may adopt and discuss how resilience and risk management are complementary approaches to traditional PD. Our arguments are supported by a case study of an engineering organisation and additional interviews conducted with members of similar organisations for purposes of validation. [ABSTRACT FROM AUTHOR]

Abstract There are three basic tasks undated for the infrastructure of railway transport: increasing the safety, providing the reliability of transportation process, and reducing the technical equipment service charge. The point and point machine are one of the most important components of railway transport infrastructure. Predicting the failures of this item remains an open question. The article presents a research carried out on the rail 1520 with the most common SP type of machine and a DC motor. At the first stage, component failure analysis based on the expert approach, was performed and the main, most critical refusals are identified, taking into account three service strategies. At the second stage, economically grounded approaches to the diagnosis and prediction of certain failures are analyzed. To substantiate the conclusions of the second stage, the results of the mathematical modeling of the critical points' failure are used. [ABSTRACT FROM AUTHOR]

Abstract Complex industrial systems are still very dependent on the operator's human errors. Many automated control systems have been developed for the needs of rail transport. The safety of train movement directly depends on some of them. In case of a malfunction during the operation of such systems, they pass into a safe state and most traffic safety tasks are transmitted to the operator or station operator. To obtain quantitative values ​​of the probability of timely execution of operations by the duty officer at the station, a functional-semantic network and a corresponding model are proposed. This work investigates the connection between the probability of timely execution of operations and the psychophysiological state of the duty officer in case of complex industrial systems problems on the railway transport. [ABSTRACT FROM AUTHOR]

Highlights • Development of a sustainable public transportation network is one of the most important factors for a city. • A prioritization analysis is carried out by using a hybrid mechanism for failure with uncertainties. • The proposed method consists of stochastic, fuzzy approaches and Delphi Method. • Identification and ranking the importance of the failures for BRT system have been clarified. • The aim is to support decision makers in taking the maintenance decisions of the vehicles by using the proposed method. Abstract Development of a sustainable public transportation network is one of the most important factors for establishing a sustainable city. Failure analysis for public transport systems is not an issue to be adequately addressed. However, this issue has great importance in terms of maintenance planning and reliability. So, this paper aims for prioritizing failures for corrective actions in Bus Rapid Transit System (BRT) by using a hybrid Multi Criteria Decision Making (MCDM) methodology. In this paper, a prioritization analysis is carried out by using a hybrid mechanism consists of stochastic, fuzzy approaches and Delphi Method for failure with uncertainties. The proposed hybrid MCDM methodology has been applied for the BRT system in Istanbul, Turkey. Both fuzzy and stochastic approaches have been applied to deal with all the uncertainty in the process. To model uncertainties discussed in fuzzy logic more precisely, type-2 fuzzy analytic hierarchy process (AHP) method has been used to determine the weights of the criteria for failures. After the criteria's weights are clarified, a stochastic TOPSIS method is adopted for obtaining the ranking of the failures in the better model of the probabilistic uncertainty. At all these stages, Delphi method also has been applied to obtain experts' evaluations. These evaluations are used as input for the proposed MCDM methodology. Finally, identification and ranking the importance of the failures for BRT system have been clarified. So that it is aimed to support decision makers in taking the maintenance decisions of the vehicles by using the proposed approach. [ABSTRACT FROM AUTHOR]

Abstract Background Metal on metal hip resurfacing (MoM-HR) is an alternative to total hip arthroplasty in young and active patients. The purpose was to determine the survivorship of MoM-HR procedures performed in patients aged 45 years and younger assessing patient-reported outcome measures (PROMs) at minimum 5-year follow-up. Methods All 217 patients equal to or younger than 45 years of age at the time of surgical intervention presenting to our center with MoM-HR between May 2002 and May 2011 were prospectively followed. Baseline demographic data, preoperative and postoperative radiographic measurements, and validated PROMs were obtained (Hip Disability and Osteoarthritis Outcome Score, Western Ontario and McMaster Universities Osteoarthritis Index, and University of California, Los Angeles Activity Score). Survivorship was calculated using Kaplan-Meier analysis, and risk factors for failure were identified using multivariate regression analysis. Results The overall survivorship excluding septic failures was 94.6% and 93.8% at 5 and 10 years, respectively. Aseptic loosening of the acetabular component was the most common mode of failure (11/20 cases). Gender, head size, and acetabular abduction angle had no significant effect on survivorship. Significant improvements in PROMs were seen for Hip Disability and Osteoarthritis Outcome Score, Western Ontario and McMaster Universities Osteoarthritis Index, and University of California, Los Angeles Activity Scale (P <.001). Conclusion This study indicates that MoM-HR is a suitable option for young individuals, as demonstrated through improved functional scores and low revision rates. The survivorship of HR in the younger than 45 age-group was similar to that of total hip arthroplasty, as well as HR in older patients. Given the proposed benefits of HR, this procedure may be viewed as a viable option in patients aged younger than 45 years. [ABSTRACT FROM AUTHOR]

A unique feature of battery electric vehicles (BEV) is their regenerative braking system (RBS) to recapture kinetic energy in deceleration maneuvers. If such a system is triggered via gas pedal, most deceleration maneuvers can be executed by just using this pedal. This impacts the driving task as different deceleration strategies can be applied. Previous research has indicated that a RBS failure leading to a sudden reduced deceleration represents an adverse event for BEV drivers. In the present study, we investigated such a failure's impact on the driver's evaluation and behavior. We conducted an experiment on a closed-off test track using a modified BEV that could temporarily switch off the RBS. One half of the 44 participants in the study received information about an upcoming RBS failure whereas the other half did not. While 91% of the drivers receiving prior information noticed the RBS failure, only 48% recognized it in the "uniformed" group. In general, the failure and the perception of its occurrence influenced the driver's evaluation and behavior more than receiving prior information. Nevertheless, under the tested conditions, drivers kept control and were able to compensate for the RBS failure. As the participants drove quite simple maneuvers in our experiment, further studies are needed to validate our findings using more complex driving settings. Given that RBS failures could have severe consequences, appropriate information and warning strategies for drivers are necessary. [ABSTRACT FROM AUTHOR]

The introduction of biologic disease–modifying anti-rheumatic drugs (bDMARDs) has dramatically changed the management of rheumatoid arthritis (RA). However, in a real-life setting about 30–40% of bDMARD treated patients experience drug discontinuation because of either inefficacy or adverse events. According to international recommendations, to date the best strategy for managing first-line bDMARD failures has not been defined yet and available data (especially on TNF inhibitors [TNFis]) seem to drive toward a personalized approach for the individual patient. Some TNFi partial responders may benefit from optimization of concomitant methotrexate therapy or from switching to a different concomitant sDMARD such as leflunomide. Conversely, apart from infliximab, TNFi dose escalation seems to be poor efficacious and poor cost-effective compared with alternative strategies. Albeit counterintuitive, the use of a second TNFi after the failure of the first-one (cycling strategy) is supported by clear evidences and has become widespread in the 2000s as the result of the limited alternative options till the introduction of bDMARDs with a mechanism of action other than TNF blockade. Nowadays, the use of abatacept, rituximab, tocilizumab, or JAK inhibitors as second-line agent (swapping strategy) is strongly supported by RCTs and real-life experiences. In the absence of head-to-head trials directly comparing these two strategies, meta-analyses of separated RCTs failed to find significant differences in favor of one or another choice. However, results from most observational studies, including well designed prospective pragmatic randomised analyses, demonstrated the superiority of swapping over cycling approach, whereas only few studies reported a comparable effectiveness. In this review, we aimed to critically analyze all the potential therapeutic options for the treatment of first-line bDMARD failures in order to provide a comprehensive overview of available strategies to be applied in clinical practice. [ABSTRACT FROM AUTHOR]

An important requirement imposed on storage batteries nowadays is to have sufficient capacity. At the same time a high level of availability, reliability and safety is required as well. Our intention is to determine a capacity degradation threshold and the moment the soft failure of a graphite supercapacitor (SC) occurs. If we do not take into account the idle state, the functioning of the supercapacitor might be expressed by charging and discharging processes under different operating conditions given by the allowed extent of SC design. When looking for the degradation threshold and the moment of soft failure occurrence we performed the experimental part of measuring in the climatic chamber. We performed and recorded the processes of SC charges and discharges at different temperatures: 40 °C, 25 °C and −42 °C and at different charging and discharging currents: 2A, 4A, 6A and 8A. The experimental results were used to model mathematically the SC discharge process. Appropriate tools used for SC discharge are diffusion processes. In this case we apply a Wiener process with drift and an Itô process. [ABSTRACT FROM AUTHOR]

The industry of electric cars has been rising significantly in the last few years. This significant growth is impulsed by lithium-ion batteries (LIBs). LIBs are a stable technology that is the largest applied for storing energy systems in several sectors like electric mobility, laptops, and cell phones. However, LIBs are still sensible and must operate under controlled conditions to avoid failures and anomalies that can cause security and performance issues. Therefore, it is crucial to identify the possible failures in the initial stage. In order to help the precocious failure identification, some data-driven have been impulsed by Machine Learning (ML) techniques to diagnose failures as soon as possible. Following this direction, this work presents the application of six classification ML models to identify failures in LIBs. In order to generate the dataset, the main parameters of eight lithium-ion 18650 cells were collected under four different cases of abuse: overcharging (OC), over-discharging (OD), external short-circuit (ESC) and overheating (OH). The confusion matrix and Sensitivity were used to evaluate and compare the models. The work shows that, on average, the models could detect a failure with the Sensitivity greater than 94% for mechanical, electrical, and thermal failures. Furthermore, the RF model had the better performance of all, with the Sensitivity greater than 97%. In conclusion, according to the excellent results, this approach can be used in LIBs to detect failures in the initial stage. Due to the excellent results, the evolution of this study is embedded this study in the vehicle to classify abuses online to reduce the chances of security and performance issues. • Failures in lithium-ion batteries reduce the battery lifetime. • Three groups of failures are present in LIB: mechanical, electrical, and thermal. • Data-driven combined with Machine Learning techniques improve the detection of failures as sooner as possible and in real-time. • Construction of a mini packing of batteries to generate data. • Random Forest was the best model to detect failures in LIB. [ABSTRACT FROM AUTHOR]

Development of deposits of water-soluble minerals is connected with the risk of the accidents caused by the destruction of the waterproof stratum, and, as a consequence, water breakthrough into the mines. Thereupon, besides the problem of the mine's loss the problem of stability of the massif uppermost part appears. This part includes the foundations of buildings and serves as the base for railways and highways, bridges, dams, pipelines and etc. At the present stage of remote geophysical techniques of monitoring and prediction of such negative natural and technic origin, processes methods of high-resolution seismic survey on reflected waves have been developed most of all. In addition to prompt acquisition of physical and geological models of the section, the results of seismic observation's interpretation are proposed to be used as a part of parametric support for geomechanical calculations, which makes possible to predict rock mass stability in the range of transport facilities located above the mines. [ABSTRACT FROM AUTHOR]

For a telecommunication operator, the effective detection of access and aggregation network failures is the key to providing continuous service. Although there are many monitoring systems on the market, analysis has shown that there is no possibility of automatically detecting all failures using standard monitoring systems. In this article, an innovative option for failure detection is proposed, based on correlation analysis of data retrieved in real time from the network. A key source of data is the Remote Authentication Dial-in User Service (RADIUS) which records events giving information about a user’s Point-to-Point Protocol (PPP) session state sent to the monitoring system. It is shown here that the proposed solution enables an operator to detect all network events affecting customers. The detection of a greater number of events enables the operator to react quickly to them and to restore services to users as soon as possible, which ultimately improves the quality and continuity of provided services. [ABSTRACT FROM AUTHOR]

Wind power generation of electricity has gained popular support because of its low environmental impact and its low costs relative to other renewable energy sources. However, concerns have been raised in the power sector that wind power generation will come at the price of increased damage to other power generators. Wind power generation is naturally volatile which requires other power sources to start up and shut down in accordance with weather conditions, which for instance coal or gas generators are in general not built to do. The previous literature has used simulations to show that the damage done and the associated costs can be substantial. We use a dataset containing all reported failures in the Nordic electricity market Nord Pool and data for Danish wind power generation. The analysis shows that for both Denmark and the rest of Nord Pool the short-term costs associated with the volatility of wind power generation are non-significant. [ABSTRACT FROM AUTHOR]

Internet designed over 40 years ago was originally focused on host-to-host message delivery in a best-effort manner. However, introduction of new applications over the years have brought about new requirements related with throughput, scalability, mobility, security, connectivity, and availability among others. Additionally, convergence of telecommunications, media, and information technology was responsible for transformation of the Internet into an integrated system enabling accessing, distributing, processing, storing, and managing the payload of these messages. Users are now visibly more interested in receiving / accessing information independently of the network location of its host. This consideration in turn revived the interest in named data-driven networking (a.k.a. Information-Centric Networking - ICN). Instead of assuming that networks are limited to the manipulation of network locator space, the basic assumption underneath is that information can be named, addressed, and matched independently of its network location leaving in turn the possibility to match message delivery delay requirements. In this paper, we summarize our research conducted in order to bring a completely different view / perspective of network resilience, originally defined as the ability of a network to assure an acceptable level of service in the face of various faults and challenges to normal operation. That is, instead of maintaining network reachability independently of its actual utility to the “end-points”, our research aimed at exchanging and confronting the key principles that would enable an information-driven resilience (networked) scheme. More precisely, knowing that the user utility function is mainly driven nowadays by information-related criteria such as accessibility (reachability), how to design network resilience schemes that would be directed toward that goal. The main challenge is thus: can one design resilience schemes that combine maximization of end-point utility function and minimization of the network-related cost? [ABSTRACT FROM AUTHOR]

Presence of uncertainties caused by unforeseen malfunctions in actuation or measurement systems or changes in aircraft behaviour could lead to aircraft loss-of-control during flight. This paper considers sparse online Gaussian Processes (GP) adaptive augmentation for Incremental Backstepping (IBKS) flight control. IBKS uses angular accelerations and control deflections to reduce the dependency on the aircraft model. However, it requires knowledge of the relationship between inner and outer loops and control effectiveness. Proposed indirect adaptation significantly reduces model dependency. Global uniform ultimate boundness is proved for the resultant GP adaptive IBKS. Conducted research shows that if the input-affine property is violated, e.g., in severe conditions with a combination of multiple failures, the IBKS can lose stability. Meanwhile, the proposed sparse GP-based estimator provides fast online identification and the resultant controller demonstrates improved stability and tracking performance. [ABSTRACT FROM AUTHOR]

• Investigation of the reliability of wind turbines contained within a modern windfarm located in Turkey over the first two years of commercial operations. • Categorise wind turbine SCADA alarms into applicable subsystems and components. • Present comprehensive early lifetime reliability data from a number of wind turbines within the windfarm and identify the most critical subsystems and components of Type III wind turbines. • 'Safety' factors followed by 'electrical systems' were identified to cause the most failure rates and subsequent downtime. Operations and maintenance costs, and unplanned downtime accounts for a significant proportion of the total expenditure of windfarms. Therefore, reduction of these costs is essential, which requires a better understanding of the wind turbines' reliability in terms of failure rates and downtime with operational lifetime. Failure rates and downtime are generally logged using condition monitoring systems, which mainly focus on Supervisory Control and Data Acquisition (SCADA) alarm signals. The aim of this paper is to use SCADA alarm statistics to provide a new failure rate and downtime survey and thus to evaluate reliability performance of the major wind turbine components and subsystems. The paper focuses on a modern onshore windfarm located in Turkey with Type-III wind turbines over the course of the first two years of operations, which is the first time reliability data from Turkey has been published in literature. The presented data can help to provide a better understanding of early life operations, since all maintenance activities, as well as stoppages that caused the wind turbines not to generate electricity were considered in this paper. Furthermore, the evaluation and categorisation of the recorded SCADA alarms, their origins and whether they were associated with planned or unplanned downtime is presented. This analysis shows that early life modern wind turbines have the highest alarm rates and downtime associated with 'safety' factors, followed by the 'electrical systems', which was found to be the most critical (or unreliable) subsystem. The presented results therefore suggest that early life focus should be on the electrical systems of wind turbines for maximising their operating time and availability. Monthly distributions of both SCADA alarms and downtime rates are also presented to highlight the effects of environmental conditions. [ABSTRACT FROM AUTHOR]

Sofia subway is already in operation for 18 years although its network expansion continues. At the bottom of its development lay the accumulated experiences from the cities like Moscow, St. Petersburg, Paris, Vienna, Berlin and others. Sofia is a city with more than 2000 years of history; with several archaeological layers and diverse geological and tectonic conditions. All these characteristics are a prerequisite for complex technical solutions and many challenges to the engineers when they meet unexpected surprises in the geological profiles or underground infrastructure. The report will present to your attention four situations where along the tunnels route there were unexpected faults or water from the water sewerage network appearing. The above is accomplished with description of the technological solutions to such situations and applied modern geophysical surveys for rapid diagnosis of failures. [ABSTRACT FROM AUTHOR]

Background: Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are important markers in the evaluation and treatment of painful total knee arthroplasty (TKA). Elevation of both markers usually occurs with infected TKAs while a normal ESR and CRP usually point to aseptic causes for failure. The purpose of this study is to compare (1) rate of revision, (2) infection, and (3) reason for reoperation in a group of patients undergoing revision TKA with a single abnormality in either ESR or CRP in an otherwise negative conventional infection work-up compared to patients with normal preoperative ESR and CRP.Methods: We retrospectively reviewed 791 consecutive revision TKAs performed at our institution between years 2004 and 2011. Following exclusion for infection, periprosthetic fracture, prior revision TKA, positive cultures, incomplete records, and patients with less than 24-month follow-up, a total of 228 aseptic revisions (89 knees with 1 abnormal serologic marker) were available for final analysis. No patients met the current established criteria for infection. All knees underwent revision TKA using antibiotic-impregnated cement. The 2 groups were compared in terms of overall survivorship, infection rate, and rate and causes of subsequent aseptic revision.Results: The average follow-up was 60 months (24-110). There were no significant differences between the 2 groups in terms of age, sex, American Society of Anesthesiologists class, and Charlson comorbidity index. A preoperative abnormality of either ESR or CRP significantly increased the risk for reoperation for all reasons (odds ratio [OR], 3.2; P = .0028), infection (OR, 4.0; P = .034), and revision for aseptic loosening (OR, 3.69; P = .044). There were no differences in reoperations for any other reason. The average time to revision in the study group was 28.3 months compared to 40.0 months in the control group (P = .213).Conclusion: A single abnormality in either the ESR or CRP increased the likelihood of both infection and reoperation following revision TKA. Conventional methods and criteria for infection detection may not be sufficiently sensitive or specific in these cases. Further work-up with additional modalities may help increase the confidence of aseptic failure before revision TKA. [ABSTRACT FROM AUTHOR]

The paper presents a new physical model describing the processes in materials and electronic devices under the influence of cosmic rays in microgravity. The model identifies specific features of formation of the area of radiation defects (ARD) in the electronic materials in microgravity. The mechanism of interaction between the ARD and memory modules in microgravity causing malfunction and failure of onboard electronics is considered. The results of failure of memory modules under real conditions are presented. [ABSTRACT FROM AUTHOR]

Medieval and masonry bell towers are highly vulnerable to suffer strong earthquake damage due to the mechanical and physical characteristics of masonry and other important factors. An approach for the seismic vulnerability reduction of masonry towers with external prestressing is proposed. The devices are vertically and externally located in order to be removable when needed. The characteristic flexural failure mode of medieval towers and the shear mechanism of bell towers are simulated. Both failure modes are in agreement with earthquake damage in similar towers. Medium prestressing level enhances force capacity of towers failing by bending without reducing ductility. High prestressing level slightly reduces the displacement capability of towers failing ductile. In case of belfry failure, both prestressing levels permit to increase displacement but lower force than towers failing by bending. The proposed medium prestressing level is the optimal for masonry towers and other slender structures failing by bending and shear. [ABSTRACT FROM AUTHOR]

The process-oriented design and implementation of concurrent systems have important advantages. However, it is challenging to verify the consistency of process communications between the design and the implementation. To deal with such a challenge, we construct a formal framework for designing, implementing and verifying the consistency of process communications. In this framework, we use Failures in Communicating Sequential Processes (CSP), Erasmus and Category Theory as the foundation. The framework is illustrated by using a running example. [ABSTRACT FROM AUTHOR]

Rolling contact fatigue (RCF) of a variety of bearing steels was studied with a ball-on-rod configuration rig. Systematic sectioning of the specimens across the spalls revealed the presence of oxide near the cracks. Further characterisation of this phase using electron microscopy revealed that it was formed during testing, after crack initiation. It is highlighted that the discovered oxide could, in some cases, be mistaken for a non-metallic inclusion. The authors suggest that attributing RCF failure initiation to non-metallic inclusions should not only rely on optical microscopy but also on EDX measurements, as this reveals a composition inconsistent with non-metallic inclusions. A mechanism for the in situ formation of the oxide is suggested and its possible role on failure is discussed. [ABSTRACT FROM AUTHOR]

Consider a system in which tasks of different execution times arrive continuously and have to be executed by a set of machines that are prone to crashes and restarts. In this paper we model and study the impact of parallelism and failures on the competitiveness of such an online system. In a fault-free environment, a simple Longest-In-System scheduling policy, enhanced by a redundancy-avoidance mechanism, guarantees optimality in a long-term execution. In the presence of failures though, scheduling becomes a much more challenging task. In particular, no parallel deterministic algorithm can be competitive against an off-line optimal solution, even with one single machine and tasks of only two different execution times. We find that when additional energy is provided to the system in the form of processing speedup, the situation changes. Specifically, we identify thresholds on the speedup under which such competitiveness cannot be achieved by any deterministic algorithm, and above which competitive algorithms exist. Finally, we propose algorithms that achieve small bounded competitive ratios when the speedup is over the threshold. [ABSTRACT FROM AUTHOR]

Objective To assess the 5-year survival of metal-ceramic and all-ceramic tooth-supported single crowns (SCs) and to describe the incidence of biological, technical and esthetic complications. Methods Medline (PubMed), Embase, Cochrane Central Register of Controlled Trials (CENTRAL) searches (2006–2013) were performed for clinical studies focusing on tooth-supported fixed dental prostheses (FDPs) with a mean follow-up of at least 3 years. This was complimented by an additional hand search and the inclusion of 34 studies from a previous systematic review [1,2] . Survival and complication rates were analyzed using robust Poisson's regression models to obtain summary estimates of 5-year proportions. Results Sixty-seven studies reporting on 4663 metal-ceramic and 9434 all-ceramic SCs fulfilled the inclusion criteria. Seventeen studies reported on metal-ceramic crowns, and 54 studies reported on all-ceramic crowns. Meta-analysis of the included studies indicated an estimated survival rate of metal-ceramic SCs of 94.7% (95% CI: 94.1–96.9%) after 5 years. This was similar to the estimated 5-year survival rate of leucit or lithium-disilicate reinforced glass ceramic SCs (96.6%; 95% CI: 94.9–96.7%), of glass infiltrated alumina SCs (94.6%; 95% CI: 92.7–96%) and densely sintered alumina and zirconia SCs (96%; 95% CI: 93.8–97.5%; 92.1%; 95% CI: 82.8–95.6%). In contrast, the 5-year survival rates of feldspathic/silica-based ceramic crowns were lower ( p < 0.001). When the outcomes in anterior and posterior regions were compared feldspathic/silica-based ceramic and zirconia crowns exhibited significantly lower survival rates in the posterior region ( p < 0.0001), the other crown types performed similarly. Densely sintered zirconia SCs were more frequently lost due to veneering ceramic fractures than metal-ceramic SCs ( p < 0.001), and had significantly more loss of retention ( p < 0.001). In total higher 5 year rates of framework fracture were reported for the all-ceramic SCs than for metal-ceramic SCs. Conclusions Survival rates of most types of all-ceramic SCs were similar to those reported for metal-ceramic SCs, both in anterior and posterior regions. Weaker feldspathic/silica-based ceramics should be limited to applications in the anterior region. Zirconia-based SCs should not be considered as primary option due to their high incidence of technical problems. [ABSTRACT FROM AUTHOR]

Objective To assess the 5-year survival of metal-ceramic and all-ceramic tooth-supported fixed dental prostheses (FDPs) and to describe the incidence of biological, technical and esthetic complications. Methods Medline (PubMed), Embase and Cochrane Central Register of Controlled Trials (CENTRAL) searches (2006–2013) were performed for clinical studies focusing on tooth-supported FDPs with a mean follow-up of at least 3 years. This was complemented by an additional hand search and the inclusion of 10 studies from a previous systematic review [1] . Survival and complication rates were analyzed using robust Poisson's regression models to obtain summary estimates of 5-year proportions. Results Forty studies reporting on 1796 metal-ceramic and 1110 all-ceramic FDPs fulfilled the inclusion criteria. Meta-analysis of the included studies indicated an estimated 5-year survival rate of metal-ceramic FDPs of 94.4% (95% CI: 91.2–96.5%). The estimated survival rate of reinforced glass ceramic FDPs was 89.1% (95% CI: 80.4–94.0%), the survival rate of glass-infiltrated alumina FDPs was 86.2% (95% CI: 69.3–94.2%) and the survival rate of densely sintered zirconia FDPs was 90.4% (95% CI: 84.8–94.0%) in 5 years of function. Even though the survival rate of all-ceramic FDPs was lower than for metal-ceramic FDPs, the differences did not reach statistical significance except for the glass-infiltrated alumina FDPs ( p = 0.05). A significantly higher incidence of caries in abutment teeth was observed for densely sintered zirconia FDPs compared to metal-ceramic FDPs. Significantly more framework fractures were reported for reinforced glass ceramic FDPs (8.0%) and glass-infiltrated alumina FDPs (12.9%) compared to metal-ceramic FDPs (0.6%) and densely sintered zirconia FDPs (1.9%) in 5 years in function. However, the incidence of ceramic fractures and loss of retention was significantly ( p = 0.018 and 0.028 respectively) higher for densely sintered zirconia FDPs compared to all other types of FDPs. Conclusions Survival rates of all types of all-ceramic FDPs were lower than those reported for metal-ceramic FDPs. The incidence of framework fractures was significantly higher for reinforced glass ceramic FDPs and infiltrated glass ceramic FDPs, and the incidence for ceramic fractures and loss of retention was significantly higher for densely sintered zirconia FDPs compared to metal-ceramic FDPs. [ABSTRACT FROM AUTHOR]

• Oversimplified models could lead to inaccurate conclusions in cascading failure predictions. • Consideration of protection mechanisms is essential to obtain more realistic models of power grids. • Simplistic, ODE-based models tend to overestimate the size of cascading failures. In this work we show that simple classic models of power grids, albeit frequently utilized in many applications, may not be reliable for investigating cascading failures problems. For this purpose, we develop a novel model, based on a structure-preserving approach, to obtain a network-based description of a power grid, where nodes correspond to generators and buses, while the links correspond to the physical lines connecting them. In addition, we also consider classic voltage and frequency protection mechanisms for lines and buses. Considering the Italian power grid as a case study of interest, we then investigate the propagation of an initial failure of any line of the power system, and compare the predicted impact of the failure according to different assumptions in the model such as the presence or absence of protection mechanisms and a simplified description of the system dynamics. In particular, it can be observed that more realistic models are crucial to determine the size of the cascading failure, as well as the sequence of links that may be involved in the cascade. [ABSTRACT FROM AUTHOR]

• Studying the main failure of the strain gauge type pressure sensors. • Mathematical modeling of a strain gauge pressure sensor in the presence of bubbles in the interface liquid. • Solving differential equations of the membrane and sensing plate displacement coupled with the nonlinear bubble dynamics equation. • The effect of the existence of bubbles on the dynamic response of the sensor. • Time-domain response of the sensing plate considering different types of applied dynamic pressure as step, single pulse, harmonic, etc. • Transient response of the sensor considering bubbles with different size. This paper studies one of the major failures, that may occur in macro-scale strain gauge pressure sensors as well as micro-scale ones. The leakage in the interface fluid chamber of the sensor causes the air to be trapped especially in the form of bubbles in the interface liquid near the boundaries. In this work, mathematical modeling of a strain gauge pressure sensor in the presence of the trapped micro-scale bubbles in the interface liquid is presented. The governing equations of displacement of the membrane and sensing plate coupled with the nonlinear dynamic equation of bubbles are solved simultaneously utilizing the Galerkin weighted residual method. The transient response of the sensor in the presence of bubbles is investigated considering different types of applied dynamic pressure as step, single pulse, repetitive pulse, and harmonic. Results indicate that when a higher percentage of the interface oil is filled with bubbles, the maximum overshoot in the response of the sensor reduces, while, the peak time, rise time, and also settling time in the response of the sensor increases. A delay is observed in the time-domain response of the sensor due to the reduction of speed of transferring data from the membrane to the sensing plate caused by the bubbles in the interface liquid. [ABSTRACT FROM AUTHOR]

Highlights: [•] We present analysis of a failed stainless steel molten salt corrosion experiment. [•] We examine corrosive gas evolution between molten salt and insulation. [•] Corrosive gas leads to the structural failure of the high temperature system. [•] Stainless steel shows heavy attack through vapor fluorination. [Copyright &y& Elsevier]

Highlights: [•] Common ladder setup methods were analyzed for accuracy and safety. [•] Setup angles were measured and test subjects were given a questionnaire. [•] Engineering analysis was performed to determine number of slide-out failures. [•] Many test subjects were confused and dangerous conditions were identified. [ABSTRACT FROM AUTHOR]

Highlights: [•] We examine failure criteria for anisotropic material to apply to wood. [•] Hill, Tsai-Hill, Tsai-Wu, Hoffman and Norris failure criteria were studied. [•] Failure envelope curves for two Brazilian wood species were performed. [•] Comparisons with envelopes curves from experimental results were provided. [•] Hoffman criterion presented the best strength evaluation for these wood species. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cumalıkızık traditional timber structures had been built with a holistic design understanding. [•] Faulty repairs by the building owners and new add-ons created significant hazards to the timber structures. [•] Timber beams formed in the stone walls has an important function in the compensation for the tensile stresses. [•] Adobe-filled timber structural system resist the earthquake forces in harmony. [•] The timber joint details solved with the most appropriate methods. [ABSTRACT FROM AUTHOR]

Highlights: [•] Efficiency of FRP composites in restoring shear strength of sulfate-damage beams. [•] Evaluating anchorage of FRP strips using FRP sheets. [•] Analytical predictions of shear capacity of beams matched experimental results. [•] Use of FRP strips and sheets helped restoring original mechanical properties. [•] FRP composite enhanced crack resistance, and delayed the onset of initial cracking. [Copyright &y& Elsevier]

Highlights: [•] Column shear-axial failure does not necessarily constitute structural collapse. [•] A column failure leads to an increasing shear demand in columns above and below. [•] Columns above a failed column become significantly more susceptible to failure. [•] Shear-axial failure of columns over the same column line is not significantly damaging. [•] Axial failure of a column causes an immediate drop in compression of columns above. [ABSTRACT FROM AUTHOR]

Abstract: This paper reviews the analysis and design of telecommunication structures and presents the main problems observed for various types of structures. The nation of Portugal is selected for a case study, and more specifically, the evolution of Portuguese structural design standards for telecommunications systems is summarised using comparative analyses that cover a subset of the most relevant topics for design, including wind profiles, drag coefficients, dynamic effects and reliability classes. These analyses focus on characterisation of the effects of wind action, which plays a fundamental role in the behaviour and design of these structures. Following the comparative analyses of standards, the more common problems observed over the past 20years in guyed masts and towers located in Portugal are presented and discussed. [Copyright &y& Elsevier]

Abstract: A nonlinear finite element analysis (NLFEA) model is proposed, validated then expanded to predict the contribution of fiber reinforced polymer (FRP) composites in regaining structural performance and controlling failure of shear-deficient and sulfate-damaged RC beams. The model was validated using experimental data, before expanded to consider the effect of FRP form (sheet against strip), and its fiber orientation (45° against 90°), and bond area (web against U-wrap) in addition to sulfate-damage level. The performance was evaluated using ultimate shear strength, stiffness, toughness, and crack-opening toughness. Furthermore, shear stress versus slip for the FRP composites, strain-depth distribution in the high shear region, and cracking modes at failure for repaired beams were generated and compared. The NLFEA results showed that repairing shear-deficient and sulfate damaged RC beams with various configurations of (carbon and glass) FRP strips and sheets helped enhancing their loading carrying capacity by (10–39)% and (4–32)%, respectively. External 90° FRP U-wrap sheet provided larger increase in ultimate shear capacity than that with 90° FRP web sheets. As expected, carbon and glass FRP web strips showed better structural performance when oriented at 45° rather at 90°. Except for that with U-wrap FRP sheet, repair techniques with glass fibers imparted better overall structural performance to repaired beams than that of the FRP composites with carbon fibers. [Copyright &y& Elsevier]

Abstract: In this study, the analysis on broken of architectural glass panel subjected to blast loading is investigated. The architectural glass panel breaks up into fragments when it is overloaded by the external blast. The projection velocity and splash distance of glass fragments are very important parameters to establish fragment flight trajectory. In this paper, the fragment projection velocity is formulated based on energy principles, and the flight path is proposed by solving the acceleration equations established according to the variations of motion direction and force direction of the fragment. Explosive tests of architectural glass panel were carried out in the field test site to investigate the pressure loss effect on the projection velocity during the deformation of the panel. Empirical expressions of glass fragment flight trajectory are developed using a combined theoretical and experimental approach, which may be used to estimate the hazard from broken glazing. [Copyright &y& Elsevier]

Abstract: The causes of recent fires in hydrocarbon heaters are discussed in this paper. In particular, failures are chosen for which root causes involve trying to get around existing operational shortcomings by making changes to control, instead of carrying out a proper Root Cause Analysis to identify actual causes of deficiencies. In one case, the heater would extinguish due to the poor characteristics of fuel gas. A restart routine was devised, in which previous purging was avoided. In the other case, turning off one burner would turn off the remaining. Instead of addressing the reason why a burner would turn off, the operator modified gas inlet control so that the remaining burners would remain on. Details are given of the chain of events that led to these failures. It is concluded that heaters should be carefully chosen or designed to meet specific operation requirements. Modifications should be avoided whenever possible and carefully planned, in association with the manufacturer when they are unavoidable. In every case, safety systems should be in accordance with modern safety standards. [Copyright &y& Elsevier]

Abstract: Probabilistic annotations generalise standard Hoare Logic to quantitative properties of probabilistic programs. They can be used to express critical expected values over program variables that must be maintained during program execution. As for standard program development, probabilistic assertions can be checked mechanically relative to an appropriate program semantics. In the case that a mechanical prover is unable to complete such validity checks then a counterexample to show that the annotation is incorrect can provide useful diagnostic information. In this paper, we provide a definition of counterexamples as failure traces for probabilistic assertions within the context of the pB language , an extension of the standard B method to cope with probabilistic programs. In addition, we propose algorithmic techniques to find counterexamples where they exist, and suggest a ranking mechanism to return ‘the most useful diagnostic information’ to the pB developer to aid the resolution of the problem. [Copyright &y& Elsevier]

Abstract: The present paper describes the benefits of using a common failure assessment template when carrying out failure assessments of buildings. A common failure template is proposed. This template is targeted for failures which occur in timber buildings. This template has been tested by various experts in Europe and positive feedback has been received so far. However, it is foreseen that further developments on this procedure will probably need to be done. [Copyright &y& Elsevier]

Abstract: Natural and anthropogenic caves may represent a potential hazard for the built environment, due to the occurrence of instability within caves, that may propagate upward and eventually reach the ground surface, inducing the occurrence of sinkholes. In particular, when caves are at shallow depth, the effects at the ground surface may be extremely severe. Apulia region (southern Italy) hosts many sites where hazard associated with sinkholes is very serious due to presence of both natural karst caves and anthropogenic cavities, the latter being mostly represented by underground quarries. The Pliocene–Pleistocene calcarenite (a typical soft rock) was extensively quarried underground, by digging long and complex networks of tunnels. With time, these underground activities have progressively been abandoned and their memory lost, so that many Apulian towns are nowadays located just above the caves, due to urban expansion in the last decades. Therefore, a remarkable risk exists for society, which should not be left uninvestigated. The present contribution deals with the analysis of the most representative failure mechanisms observed in the field for such underground instability processes and the factors that seem to influence the processes, as for example those causing weathering of the rock and the consequent degradation of its physical and mechanical properties. Aimed at exploring the progression of instability of the cavities, numerical analyses have been developed by using both the finite element method for geological settings represented by continuous soft rock mass, and the distinct element method for jointed rock mass conditions. Both the effects of local instability processes occurring underground and the effects of the progressive enlargement of the caves on the overall stability of the rock mass have been investigated, along with the consequent failure mechanisms. In particular, degradation processes of the rock mass, as a consequence of wetting and weathering phenomena in the areas surrounding the caves, have been simulated. The results obtained from the numerical simulations have then been compared with what has been observed during field surveys and a satisfactory agreement between the numerical simulations and the instability processes, as detected in situ, has been noticed. [Copyright &y& Elsevier]

Abstract: The safety of a population also relies on the safety of the water pipe network systems. Good quality water supplying is required. A failure of these types of systems may have a huge social impact. The theory of vulnerability of water pipe networks intends to give a contribution in this context by tracing the vulnerable parts of the system and, consequently, giving guidance to increase its robustness. This theory is described in brief and supported on three water pipe networks examples. [Copyright &y& Elsevier]