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Constellations of satellites, in particular using small satellites, are very popular nowadays, because they give reduced costs and flexibility to missions. This paper considers the problem of designing a constellation of small satellites for data communication, which means getting data from platforms fixed on the surface of the Earth and sending them to ground stations using satellites. The goal is to maximize the observation times and minimize the interval between passages by these platforms and ground stations. The time evolution of the constellation under the effects of perturbation forces is also studied, and estimates of the number of new satellites that need to be added to the constellation to keep a constraint of maximum revisit time below one hour are made. After that, simulations of satellite failures allow verification of the new values for the observation times and the time between visits when the constellation loses some satellites, looking for the possibility of using this constellation even in case of failures. [ABSTRACT FROM AUTHOR]

Copyright of Dyna is the property of Universidad Nacional de Colombia, Medellin, Facultad de Minas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the contemporary landscape characterized by heightened competitive pressures, adept maintenance management assumes a pivotal and strategic role in cost mitigation and profit augmentation. This paper applies the risk-based maintenance (RBM) methodology to the hydraulic system of a remotely operated vehicle (ROV) owned by an oil and gas services company. To achieve this, it was necessary to gather information on the system failures, followed by determining the critical subsystems. By analyzing the frequency and severity of identified failures, a risk matrix could be constructed. Using the "5 Whys" technique, an analytical framework was used to uncover the root causes of the failures observed in the handlers and propellant subsystems. Subsequently, a risk matrix is formulated again after the implementation of the RBM and the mitigation measures adopted by the authors to elucidate the discernible impact of the maintenance methodology on improving the availability of the ROV and the incidence of failures outlined in the study. [ABSTRACT FROM AUTHOR]

This article delves into the techniques employed for identifying failures in hard disks through the utilization of machine learning algorithms. Hard disks serve as essential components within computer systems, and as they age and undergo repetitive usage, they may manifest indications of failure or inadequate performance, culminating in data loss and system malfunction. Consequently, the early detection and anticipation of hard disk failures are of utmost significance. Recent advancements in machine learning methods have enabled the precise detection of hard disk failures within a short timeframe. Within this investigation, we explore the foundational concepts pertaining to hard disks and their failures. We scrutinize various machine learning algorithms employed for the detection of hard disk failures. Furthermore, we introduce performance evaluation metrics for failure detection models. The challenges and limitations in the detection of hard disk failures are discussed, along with potential strategies for enhancing system performance and accuracy. [ABSTRACT FROM AUTHOR]

This research focuses on the dynamic landscape of today’s competitive market, where production management must meet clients’ expectations for high-quality products and shorter lead times while managing internal disruptions due to inevitable defects and unpredictable equipment failures. Achieving these operational goals without compromising product quality, missing deadlines, or experiencing production disruptions is essential for minimizing operational expenses. The study examines the dynamics of the system’s operating costs through the development of models, mathematical formulations, optimization techniques, and algorithm proposals. It demonstrates the system’s convexity and establishes the optimal batch time for implementing the proposed methodologies. The research results show relevant failure costs of 3.51 %, overtime added costs of 4.57 %, outsourcing setup costs of 0.73 %, outsourcing variable costs of 41.82 %, quality-related costs of 2.98 %, in-house variable costs of 40.42 %, and in-house holding costs of 3.55 %. The study develops strategies for optimal overtime use to meet production targets without excessive labor costs and provides a structured framework for making informed outsourcing decisions that balance cost savings with quality and reliability considerations. Overall, the research provides a robust framework for reducing operational costs while maintaining or improving the quality and reliability of manufacturing processes [ABSTRACT FROM AUTHOR]

This paper presents a risk assessment approach for analyzing the causes of malfunction-related main engine slowdowns. A fuzzy Bayesian Network-based methodology is used to assess the factors contributing to the engine's slow-down processes. The model addresses the complexity and uncertainty inherent in maritime operations with fuzzy sets where numerous interrelated factors can affect engine performance, and the Bayesian network to capture probabilistic dependencies. It considers various potential causes of the slow-down of ship engines that the manufacturer provides. Results demonstrate the model's ability to identify the influential factors leading to engine slow-down events and quantify the overall risk. Integrating fuzzy logic and Bayesian Networks comprehensively assesses relevant risk factors. It enables maritime stakeholders to manage engine performance and improves operational safety proactively. Findings can inform decision-makers, enabling the implementation of targeted maintenance strategies, fuel quality control measures, and crew training programs in the maritime industry. [ABSTRACT FROM AUTHOR]

Summary: After a machine failure, batch schedulers typically re‐schedule the job that failed with a high priority. This is fair for the failed job but still requires that job to re‐enter the submission queue and to wait for enough resources to become available. The waiting time can be very long when the job is large and the platform highly loaded, as is the case with typical HPC platforms. We propose another strategy: when a job J$$ J $$ fails, if no platform node is available, we steal one node from another job J′$$ {J}^{\prime } $$, and use it to continue the execution of J$$ J $$ despite the failure. In this work, we give a detailed assessment of this node stealing strategy using traces from the Mira supercomputer at Argonne National Laboratory. The main conclusion is that node stealing improves the utilization of the platform and dramatically reduces the flow of large jobs, at the price of slightly increasing the flow of small jobs. [ABSTRACT FROM AUTHOR]

Introduction Upper respiratory tract infections (URTI) are common and a common cause of sick-leave for healthcare workers, and furthermore pose a threat especially for patients susceptible to other diseases. Sufficient use of respiratory protective equipment (RPE) may protect both the workers and the patients. The COVID-19 pandemic provided a unique opportunity to study the association between use of RPE and URTI in a real-life setting. The aim of this study was to examine if failure of RPE or non-compliance with RPE guidelines increases the risk of non-COVID-19 URTI symptoms among healthcare workers. Methods In a longitudinal cohort study, we collected self-reported data daily on work tasks, use of RPE, and URTI symptoms among healthcare workers with patient contact in 2 Danish Regions in 2 time periods during the COVID-19 pandemic. The association between failure of RPE or non-compliance with RPE guidelines and URTI symptoms was analyzed separately by generalized linear models. Persons tested positive for severe acute respiratory syndrome coronavirus 2 were censored from the analyses. The 2 waves of data collection were analyzed separately, as there were differences in recommendations of RPE during the 2 waves. Results We found that for healthcare workers performing work tasks with a risk of transmission of viruses or bacteria, failure of RPE was associated with an increased risk of URTI symptoms, RR: 1.65[0.53–5.14] in wave 1 and RR: 1.30[0.56–3.03] in wave 2. Also non-compliance with RPE guidelines was associated with an increased risk of URTI symptoms compared to the use of RPE in wave 1, RR: 1.28[0.87–1.87] and wave 2, RR: 1.39[1.01–1.91]. Stratifying on high- versus low-risk tasks showed that the risk related to failure and non-compliance was primarily associated with high-risk tasks, although not statistically significant. Discussion The study was conducted during the COVID-19 pandemic and thus may be affected by other preventive measures in society. However, this gave the opportunity to study the use of RPE in a real-life setting, also in departments that did not previously use RPE. The circumstances in the 2 time periods of data collection differed and were analyzed separately and thus the sample size was limited and affected the precision of the estimates. Conclusion Failures of RPE and non-compliance with RPE guidelines may increase the risk of URTI, compared to those who reported use of RPE as recommended. The implications of these findings are that the use of RPE to prevent URTI could be considered, especially while performing high-risk tasks where other prevention strategies are not achievable. [ABSTRACT FROM AUTHOR]

Copyright of Zeszyty Naukowe KUL is the property of John Paul II Catholic University of Lublin, Wydawnictwo KUL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In an internal combustion (IC) engine, the failure of engine parts due to friction and wear is a serious issue. This can be reduced by employing suitable surface modification techniques such as thermal barrier coatings, laser-assisted surface engineering techniques, carbon nanotubes, etc. These techniques help to decrease the frictional forces and improve the tribological, mechanical and corrosion-resistant properties of the engine components. This paper highlights the distinct causes of the failure of engine parts and the role of different surface modification techniques in improving the tribological and mechanical properties of the engine parts. After that, the preventive measures for engine parts failure including online condition monitoring and maintenance strategies are presented. Finally, the future scope and challenges are discussed. [ABSTRACT FROM AUTHOR]

This paper presents a reliability modelling of a two-unit ammonia/urea plant. Real maintenance data of the production plant have been used for this purpose. Four types of failure were noted: process, electrical, mechanical and instrumental failures. Both ammonia/urea formation units work in parallel and do not fail simultaneously. Various reliability indices of the plant, such as availability, busy period for repair, and expected number of repairs for each type of failure, have been obtained. Markov processes and regenerative point techniques are used for analysis. Profit analysis for the plant is also done, along with a graphical representation of various parameters. Finally, sensitivity analysis is carried out to see the impact of varied parameters on the profit function of the plant. [ABSTRACT FROM AUTHOR]

The bending behavior of one-war reinforced concrete (RC) slabs with polypropylene fibers (PF) was examined in this study under the effect of different opening ratios using the nonlinear finite element analysis (NLFEA) method. The investigated parameters include the effect of different square opening ratios between 0 and 24% and PF volume percentages between 0 and 1% with 0.1% increments. The objectives of this study were fulfilled using 88 NLFEA models with different combinations of the studied parameters, including 11 control slabs without openings. The slab's behavior was studied focusing on different structural performance characteristics, such as ductility, using energy-based and deflection-based approaches, stiffness (initial and yielding), cracking, and ultimate load strength. In addition, other structural performance parameters were considered, such as the crack opening, failure modes, and strain values, which were recorded for all specimens during the loading history. Moreover, the load-carrying capacity of the slabs was compared, looking at the NLFEA method's results and the theoretical prediction results based on the sectional analysis method. However, it was observed that the inclusion of PFs of different percentages has a superior effect on the behavior of RC slabs with small openings (less than 2% opening ratio) compared to the acceptable improvements obtained for sabs with larger opening sizes. Consequently, PF could be utilized as a replacement for conventional steel rebars for RC slabs with small openings. In addition, increasing the PF percentage increases the resulting crack-opening value at failure due to the provided stabilization effect, in addition to increasing the system's ability to sustain loads. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Concentrating solar power plants use sensible thermal energy storage, a mature technology based on molten salts, due to the high storage efficiency (up to 99%). Both parabolic trough collectors and the central receiver system for concentrating solar power technologies use molten salts tanks, either in direct storage systems or in indirect ones. But even though this is a mature technology, it still shows challenges in its implementation and operation. This paper underscores the critical importance of stringent design criteria for molten salt tanks in thermal storage technology. Focusing on the potential ramifications of design failures, the study explores various dimensions where an inadequate design can lead to severe consequences, even jeopardizing the viability of the entire technology. Key areas discussed include structural integrity, corrosion, thermal shock, thermal expansions, and others. By elucidating the multifaceted risks associated with design shortcomings, this paper aims to emphasize the necessity of thorough reviews and adherence to robust design principles for ensuring the success, safety, and sustainability of thermal storage technology. [ABSTRACT FROM AUTHOR]

Over the past few decades, Lab-on-a-chip (LoC) devices have made health diagnostics easier and cheaper by enabling rapid, hassle-free, and inexpensive measurements of different biochemical markers, properties of epidermally retrievable biofluids (e.g., sweat and interstitial fluids), etc. The miniaturization of these sensing technologies along with the integration of flexible frameworks (microfluidic assemblies and electronics) and user-friendly software have paved the way for autonomous and continuous tracking of human health parameters. However, with emerging new technologies, there are new and complex challenges, especially in the case of these miniature LoC devices. Although microfluidics-specific challenges such as analyte contamination, flow rate variability, improving detection specificity, etc. are being worked upon, the bigger question is: how reliable are these wearable devices in the long run? This perspective piece initially talks about the state-of-the-art LoC technologies that have been incorporated into wearable devices. Next, the perspective identifies some of the reliability studies conducted (as well as overlooked) on the integrated wearable electronics used. Finally, the paper discusses the challenges and future directions of research in the field of reliability of LoCbased wearable electronics. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Production Engineering / Revista Brasileira de Engenharia de Produção is the property of Brazilian Journal of Production Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Slopes are built for the purpose of extracting ore, in the case of mining, or access roads in civil works. The excavation of slopes in tropical countries is facilitated by the thick layer of soil formed from the more intense weathering when compared to other countries. However, the residence time of water in the soil is relatively longer and consequently allows the accumulation and percolation of water through rock fractures even in the dry period. These factors induce a greater probability of occurrence of ruptures. Mines in the decommissioning phase must guarantee slope stability conditions even after closure in order to comply with legislation and environmental safety. In this work, the slopes of a decommissioning mine were investigated using geophysical methods (GPR) and structural analysis of the rock mass. The results were presented in the form of radargrams that correlate distance and depth of investigation. Structural data served as the basis for the execution of kinematic analyzes for planar and wedge ruptures. The analysis of the results allowed the correlation between electromagnetic signal attenuation zones, with the presence of water and the occurrence of ruptures. Thus, the GPR results allowed the recognition of structural discontinuities, accumulation zones and water flow.Article Highlights: The radargrams obtained with the GPR clearly identified saturated and unsaturated zones of the rock mass; The radargrams identified existing fractures inside the rock mass consistent with those verified on the face of the slope. GPR has proven to be a subsurface analysis tool to be used in both mining and civil works. [ABSTRACT FROM AUTHOR]

Tailings dams have relatively high failure rates throughout the world and the consequences of these failures often result in significant loss of life and damage to the environment and property. However, the triggers and failure mechanisms are typically hypothesized and not well understood. To investigate potential triggers and the corresponding failure mechanisms, two centrifuge model tests were conducted on loose slopes made of gold tailings using a scaled viscous fluid to induce instability in flight. A numerical back-analysis was also carried out to investigate and verify the associated mechanisms. Two failure mechanisms were observed in the centrifuge tests. In the first test, large seepage forces caused sloughing at the toe. The initially drained instability at the toe induced significant positive excess pore pressures due to the loose state, as well as to the initially higher degree of saturation in the toe region, triggering localized liquefaction at the toe (undrained response). Due to the localized liquefaction, the tailings at the toe could not support the tailings upstream of the toe, triggering a retrogressive flowslide failure. In the second test, a slope failure occurred due to drained instability, i.e., failure occurred once the drained factor of safety approached unity. No liquefaction was evident, due to the initially lower degree of saturation in the toe region, as well as to the slower rate of shearing compared to the first test. As revealed by both physical and numerical simulations, the structural collapse of the soil resulted in the drained instability of the slope, which triggered a slide-to-flow failure. [ABSTRACT FROM AUTHOR]

Copyright of China Fiber Inspection / Zhongguo Xian-Jian is the property of China Fiber Inspection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objectives: To examine the impact of bisphosphonates (BPs) on dental implant treatment and alveolar bone in post-menopausal ladies. Materials and Methods: Twenty post-menopausal ladies who had at least one dental implant within the previous 5 years participated in the current study. Ten subjects were categorized into two groups: Group A had BP medication for 1.5 years, and group B received parathyroid hormone (PTH). Both groups' bone thickness and bone mineral density (BMD) were measured. Result: Group A had 5%, and group B had 5% of dental implants failures. BMD of cortical bone was 1468 ± 136 mg/mL and 1008 ± 84 mg/mL in groups A and B, correspondingly. The cortical and cancellous bone densities in both the groups were statically significant. Cortical bone thickness was insignificant in comparison. Conclusion: Both cortical and cancellous bones' bone mineral density decreased in both groups. With continued usage of BPs, the cortical bone thickness increased. [ABSTRACT FROM AUTHOR]

Copyright of Economic & Political Thought / Myśl Ekonomiczna & Polityczna is the property of Lazarski University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Middle East Studies Journal (MESJ) is the property of Middle East Studies Journal & Jordan Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Backgrounds: Long-span dental bridges may cause excessive load on abutment teeth and the periodontal area, which may lead to bridge fractures or periodontal problems. However, some reports have revealed that short- and long-span bridges can provide a similar prognosis. This clinical study aimed to investigate the technical complications associated with fixed dental prostheses (FDPs) of different span lengths. Methods: All patients with previously cemented FDPs were clinically examined during their follow-up visits. Several data related to FDPs were registered, such as design, material type, location, and type of complication. The main clinical factors analyzed were technical complications. Life table survival analyses were performed to calculate the cumulative survival rate of FDPs when technical complications were detected. Results: The study examined 229 patients with a total number of 258 prostheses and an average of 98 months of follow-up. Seventy-four prostheses suffered from technical complications, and the most common complication was ceramic fracture or chipping (n = 66), while loss of retention occurred in 11 prostheses. The long-term evaluation of long-span prostheses revealed a significantly higher technical complication rate compared to short-span prostheses (P = ,003). The cumulative survival rate for short-span FDPs was 91% in year 5, 68% in year 10, and 34% in year 15. For long-span FDPs, the cumulative survival rate was 85% in year 5, 50% in year 10, and 18% in year 15. Conclusion: Long-span prostheses (5 units or more) can be associated with a higher technical complication rate compared to short-span prostheses after long-term evaluation. [ABSTRACT FROM AUTHOR]

Background: Total ankle arthroplasty is increasingly used as a treatment for end stage ankle arthropathy. The aim of this study was to report the mid-term clinical function and survival results of Ceramic Coated Implant (CCI) ankle replacements and assess the association between the alignment of the CCI total ankle replacements and early functional outcome and complication incidence. Methods: Data of 61 patients, who received 65 CCI implants between 2010 and 2016, were obtained from a prospectively documented database. Mean follow-up time was 85.2 months (range 27–99 months). Clinical function was assessed with AOFAS questionnaire and passive range of motion (ROM). Survival analysis and elaborate radiographic analysis was performed. Furthermore, complications and reoperations were recorded for all patients. Results: Progression in ROM was most seen in the first 10 months from 21.8 degrees of passive range of motion preoperative to 27.6 degrees postoperative (p < 0.001), while the mean AOFAS gradually increased during follow-up postoperative from a mean of 40.9 points preoperative to an average of 82.5 but shows a small decline towards the end of follow-up (p < 0.001). During follow-up we recorded 8 failures (12.3%) resulting in a Kaplan-Meier survival analysis of 87.7% with a median follow-up of 85.2 months. Conclusion: We observed excellent clinical results and survival after TAA with the CCI implant with only a low mid-term complication rate. Level of evidence: Level III, prospective cohort study. [ABSTRACT FROM AUTHOR]

Detecting anomalously behaving devices in security-and-safety-critical applications is an important challenge. This article presents an off-device methodology for detecting the anomalous behavior of devices considering their power consumption data. The methodology takes advantage of the fact that every action on-board a device will be reflected in its power trace. This argument makes it inevitable for anomalously behaving device to go undetected. We transform the device's one-dimensional (1D) instantaneous power consumption signals to 2D time–frequency images using Constant Q Transformation (CQT). The CQT images capture valuable information about the tasks performed on-board a device. By applying Histograms of Oriented Gradients (HOG) on the CQT images, we extract robust features that preserve the edges of time–frequency structures and capture the directionality of the edge information. Consequently, we transform the anomaly detection problem into an image classification problem. We train a Convolutional Neural Network on the HOG images to classify the power signals to detect anomaly. We validated the methodology using a wide spectrum of emulated malware scenarios, five real malware applications from the well-known Drebin dataset, Distributed Denial of Service attacks, cryptomining malware, and faulty CPU cores. Across 18 datasets, our methodology demonstrated detection performance of ∼88% accuracy and 85% F-Score, resulting in improvements of 9–17% over other methods using power signals. [ABSTRACT FROM AUTHOR]

Copyright of Djoussour El-maarefa is the property of Association of Arab Universities and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nowadays, additive manufacturing (AM) has surpassed traditional machining in the realm of dawning manufacturing. In the case of conventional machining, where the material is removed by different processes (subtractive manufacturing), there is a possibility of warping and internal stress development. Rapid prototyping is another option to avoid all drawbacks of conventional machining in terms of manufacturing cost, time, accuracy, and quality. Rapid prototyping of a product by adding material (additive manufacturing) is gaining commercial traction. Additive manufacturing is frequently employed for the fabrication and bulk customization of all kinds of intricate geometrical designs that are absurd by traditional manufacturing techniques. Additive manufacturing techniques are broadly divided into four categories: (a) material extrusion, (b) chain polymerization, (c) laser or electron beamassisted sintering, and (d) direct writing-based processes. This article is a cutting-edge review that focuses on additive manufacturing processes and materials used in additive manufacturing. The process parameters for experimentation are chosen based on the application for which the part is designed. Some input process factors influence others for a specific response, and these critical process parameters are identified and optimized. This paper also gives a synopsis of failures associated with some additive manufacturing methods and their preventive actions. [ABSTRACT FROM AUTHOR]

Of all industrial machine components, shafts are among the most likely to be weld repaired rather than replaced. Weld repairs can be the cause or a significant contributor to the ultimate failure of shafts, even when repairs are high quality. Poor quality weld repairs can result in rapid or even immediate failure once service is resumed. Shaft welding repairs are not always performed by the original equipment manufacturer, so the engineering scrutiny that went into the initial design may not be reflected in subsequent repairs. Commercial failure analysts encounter a great number of shaft failures from all industries, and welding repairs are important in many of these cases. This paper discusses the failure analysis concerns related to weld repaired steel shafts and provides an overview of the weld repair methods as well as several failure analysis case studies. [ABSTRACT FROM AUTHOR]

Aim: The study aimed to evaluate and compare the shear bond strength (SBS) at the interface of monolithic zirconia with zirconomer (Zr) core build-up, a new type of glass ionomer cement to monolithic zirconia with composite resin core build-up material. Setting and Design: In vitro a comparative study. Materials and Methods: A total of 32 disk-shaped samples of monolithic zirconia and two distinct core build-up materials: Zr (n = 16) and composite resin (n = 16) were used. The two components, monolithic zirconia with Zr core build-up and monolithic zirconia with composite resin core build-up, were bonded using zirconia primer and self-adhesive, dual-cure cement. The samples were subsequently thermocycled, and the SBS was tested at their interfaces. The failure modes were determined using a stereomicroscope. Data were evaluated using the descriptive analysis for mean, standard deviation, confidence interval, and independent t-test for intergroup comparison. Statistical Analysis Used: Descriptive analysis, independent t-test, Chi-square test. Results: The mean SBS (megapascals) of monolithic zirconia to Zr core build-up (0.74) was statistically significant when compared to monolithic zirconia with composite resin core build-up material (7.25) (P ≤ 0.001). Zirconomer core build-up showed 100% adhesive failure; composite resin core build-up had 43.8% cohesive, 31.2% mixed, and 25.0% adhesive failures. Conclusion: When evaluating the two core build-up materials' bindings to monolithic zirconia, Zr and composite resin core build-up showed statistically significant differences. Although Zr has been demonstrated to be the optimal core build-up material; however, additional investigation is required to determine how it bonds to monolithic zirconia more effectively. [ABSTRACT FROM AUTHOR]

In this article, the performance of the composite materials of a blade prototype in terms of stiffness and mechanical strength by applying a set of load levels in the direction of flapwise loading in order to quantify and characterize the degradation of stiffness structure as a function of loading rate and number of cycles. In this concordance, a test bench was designed in CATIA V5 and manufactured and assembled in our laboratory in order to test the blade of 712 mm in length in bending to characterize the structure in terms of fatigue resistance, damage tolerance and several propositions to improve the overall blade composite structure. In fact, a bench have been designed and manufactured to test the mechanical charactristics of the blade composite structure. The results would be obtained used this experimental strategy is performed in this brief review. The mechanical testing of the blade is performed in the case of secure and structural health of the blades during the blade manufacturing. The validation of our experimental results are performed based on our previous studies of numerical simualtions of a blade composite materials of 2.5 m in length. [ABSTRACT FROM AUTHOR]

Highlights: Non-uniform matrix stresses in composites cannot be assessed against matrix strengths obtained in uniform stress states. The non-uniform matrix stresses must be converted into equivalent uniform ones called true stresses before estimating any matrix-dominated composite failure. Conversion is achieved through matrix true stress theory summarized in this paper. Selected applications for resolving several challenging problems in composite failures are highlighted. Whereas mechanics theories for isotropic materials are almost matured, only linear elastic theories for composites were essentially established. This is because only homogenized or approximated stresses are obtainable for a composite. Its mechanical properties must be estimated on a true stress level. According to Eshelby, the true stresses of the fiber are the same as its homogenized counterparts. The true stress theory for the matrix was systematically established by the author, and is reviewed and summarized in the paper. An Excel table-based program for calculating all of the possible true stress components is provided as a supplement for the reader to download. As most composite failures are caused by matrix failures, the true stress theory plays a predominant role in estimating the composite properties outside a linear elastic range. Some challenging composite failures were resolved upon the matrix true stresses, and are highlighted in the paper. [ABSTRACT FROM AUTHOR]

Copyright of Iteckne is the property of Universidad Santo Tomas, Division de Ingenierias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study examines the root causes of Public Policy implementation failures. It further explores the mechanisms that will ensure successful policy implementation within the public sector. The main objective of the study is to establish and identify the factors that impede the successful implementation of government policies and to identify possible solutions to successfully formulate and implement public policies. The study adopted a conceptual approach relying heavily on secondary data. It is understandable, that the government‘s national and local spheres should want to downplay policy failure and trumpet apparent success, but to do so risks losing an understanding of why failure is so common and how it might be eradicated or at least minimised. The study examines the robust policy design mechanisms. The study seeks to identify significant policy risks and challenges. The study examines the root causes of Public Policy implementation failures. It further explores the mechanisms that will ensure successful policy implementation within the public sector. The main objective of the study is to establish and identify the factors that impede the successful implementation of government policies and to identify possible solutions to successfully formulate and implement public policies. The study adopted a conceptual approach relying heavily on secondary data. It is understandable that the government‘s national and local spheres should want to downplay policy failure and trumpet apparent success, but to do so risks losing an understanding of why failure is so common and how it might be eradicated or at least minimised. The study examines robust policy design mechanisms. The study seeks to identify significant policy risks and challenges. It is evident, that there is an increasing awareness that policies fail on their own merits; rather their progress is dependent upon the process of implementation. To better comprehend how to refine policy support it is first instructive to appreciate the nature of policy failure, logically the reasons why things go wrong should assist to guide the search for possible solutions. Successful policy implementation consists of four determinants, which are policy design, stakeholders, and their involvement, institution, and context as well as the implementation strategy. It is very important to consider these four aspects when executing public policy because this will alleviate policy implantation failures. The study concludes with the mechanisms and solutions of successful policy implementation. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wooden sandwich panels with a corrugated core have not been the subject of scientific research so far. The anisotropic properties of the wood make it challenging to form corrugated shapes. Therefore, it is decided to determine the effect of geometric imperfections of the corrugated core made of wood veneers on the stiffness and strength of sandwich panels and the core elasticity modulus. The beams are manufactured in industrial conditions and subjected to three‐point bending. The research is carried out in the form of tests and numerical calculations. It is demonstrated that geometric imperfections of the core affect the stiffness and strength of sandwich panels. The modulus of elasticity can reach values lower by up to 37% and the strength by up to 24% compared with reference panels with an ideal, symmetrical core geometry. However, their average linear elasticity modulus (1449 MPa) indicates excellent construction properties. Under the tests, four stages of beam bending are revealed. The last stage means that panels can increase stiffness even after the core is destroyed. The corrugated core's modulus of elasticity is also determined. [ABSTRACT FROM AUTHOR]

"If terms be incorrect, then statements do not accord with facts". (Confucius) "Words form the thread on which we string our experiences". (Aldous Huxley) Semantics is a term coined by Michel Bréal (1832 to 1915) a Jewish German-French linguist referring to the Greek semantikos (= meaning) in his 1897 book, "Essai de sémantique". He was a very gifted man: for example, he was the one who suggested to Pierre de Coubertin to include the marathon in the Olympic Games and who also, with the help of a Francophile American dental practitioner, Thomas William Evans, created the "Doctorat d'Université", finally allowing American students to pursue their doctorate at a French university. [ABSTRACT FROM AUTHOR]

Many new HVAC power cable installations on wind farms, both on- and offshore, have long lengths. In contrast to traditional power cable connections of a few kilometers, the failures of those systems usually result in much higher repair and unsupplied energy costs. To support the quality assurance of newly installed cable systems as well as to create a sound basis for condition-based maintenance, this paper discusses the technical challenges of the field testing of long-length power cable systems using a damped AC testing method and also discusses the best practical applications for the testing and diagnosis of these wind farm HVAC cable systems. [ABSTRACT FROM AUTHOR]

This paper presents the model for the identification of reference points on the lifetime curve of engineering systems. This curve commonly represents the increase and decline of failure in relation to time. A direct correlation between failure rate and costs is assumed in this paper, therefore, statistical and empirical analysis of costs provided reference points. This approach is used for positioning stages of the engineering system's lifetime with a minimal number of failures and costs, regardless of whether these are acceptable or not. The following three stages are usually identified: the beginning, the stationary part and the end of life. The boundaries between them are recognized on the basis of minimum total lifetime costs and on economic lifetime costs. Model is tested on the dozers, machines frequently used in the mining industry for the earthmoving operations, and which are characterized by high operating and maintenance costs. [ABSTRACT FROM AUTHOR]

Transportation public–private partnership (PPP) projects are long-term projects that usually break the status quo of public ownership. In fact, opposition to PPP projects stems from a variety of factors, such as political influence to favor certain interest groups and high toll prices. Close examination reveals that vulnerability to societal and political domains originates at certain individual points and creates a complex web of problems as it propagates through different socioeconomic and political levels and project stages. This article attempts to unveil such complex and problematic trends by analyzing ten failed transportation PPP projects to identify critical socioeconomic and political failure factors. Employing questionnaire surveys and path analysis, a failure-mechanism model is developed to depict all possible transportation PPP project vulnerabilities to the socioeconomic and political domains. This article's failure-mechanism model could act as a vulnerability-prediction model for transportation PPP practitioners in the public and private sectors, and it can help better understand socioeconomic and political issues’ impacts to transportation PPP projects. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the clinical outcome of deantigenated equine bone (DEB) grafts in a series of patients treated with DEB at six months postaugmentation. Materials and Methods: One hundred DEB grafts were inserted in 81 patients between January 2004 and December 2006. Thirty‐two DEBs were blocks and 68 were granules (52 sinus lift and 16 guided bone regeneration [GBR] procedures performed). A total of 147 implants were inserted. A Pearson chi‐square test was used to detect any statistically significant correlation between the studied variables and early and/or late failures. Results: There were 6 early and 26 late graft failures and another 16 failures after prosthesis placement. The overall failure rate was 25% in the GBR procedures, 31.9% in sinus lift, and 54.3% with blocks, for a total complication rate of 39.5%. A statistically significant relation was detected with respect to graft type and early complications (p =.005), with a worse outcome for DEB blocks compared to granules. After provisional prosthesis restoration, 23 implants were lost, and another 41 failed after definitive prosthesis delivery, for an overall failure rate of 43.5%. The follow‐up period was 3 years after surgery. Conclusions: DEB grafting material had a very high rate of complications. Blocks had more than 50% failures, mainly in the immediate postoperative period. Other procedures such as GBR and sinus lift also showed more than 25% infections and resorption, and late failures (i.e., after‐implant placement) were also common. Our results show that DEB is less than ideal for crestal bone reconstruction. [ABSTRACT FROM AUTHOR]

Cloud applications often benefit from deployment on serverless technology Function-as-a-Service (FaaS), which may instantly spawn numerous functions and charges users for the period when serverless functions are running. Maximum benefit is achieved when functions are orchestrated in a workflow or function choreographies (FCs). However, many provider limitations specific for FaaS, such as maximum concurrency or duration often increase the failure rate, which can severely hamper the execution of entire FCs. Current support for resilience is often limited to function retries or try-catch, which are applicable within the same cloud region only. To overcome these limitations, we introduce rAFCL, a middleware platform that maintains reliability of complex FCs in federated clouds. In order to support resilient FC execution under rAFCL, our model creates an alternative strategy for each function based on the required availability specified by the user. Alternative strategies are not restricted to the same cloud region, but may contain alternative functions across five providers, invoked concurrently in a single alternative plan or executed subsequently in multiple alternative plans. With this approach, rAFCL offers flexibility in terms of cost-performance trade-off. We evaluated rAFCL by running three real-life applications across three cloud providers. Experimental results demonstrated that rAFCL outperforms the resilience of AWS Step Functions, increasing the success rate of entire FC by 53.45%, while invoking only 3.94% more functions with zero wasted function invocations. rAFCL significantly improves availability of entire FCs to almost 1 and survives even after massive failures of alternative functions. [ABSTRACT FROM AUTHOR]

Piston is the most important part in internal combustion engine. During engine operation, piston experiences stress, pressure, temperature change resulting in mechanical and thermal fatigue failure. In addition, the seizure of pistons due to their contact with the piston rings, skirt and cylinder liners is among the major problem in internal combustion engines, posing a serious threat to the efficiency of the automobiles. Hence, the aim of this review paper is to provide an overview of distinct causes of piston failures and their preventive measures. Further, the tribological and mechanical properties (hardness, elastic modulus, coefficient of friction, roughness, wear rate) of different coatings deposited by various researchers on piston/cylinder liner/piston ring are summarized. These results help the researchers in selecting an appropriate coating material composition, coating process, and parameters for a particular piston/cylinder liner/piston ring material to enhance the life of piston system. So, that any unwanted damage of piston system due to stress, pressure, fatigue, wear and friction could be minimized. [ABSTRACT FROM AUTHOR]

This paper proposes an optimal sizing strategy for water storage reservoirs that takes into account the minimum allowed number of failure periods (measure of reliability) and the maximum allowed failure magnitude (measure of vulnerability). The optimization model follows the standard operating policy for reservoir release decision—as in typical design procedures that account for failure—and is compared to an alternative mixed-integer linear programming model that uses an open-loop release policy. Deterministic and implicit stochastic versions of the model are presented, which perform efficiently for several example problems, indicating that higher storage capacities are required for higher sustainability (more reliable and less vulnerable operation) and lower risk. [ABSTRACT FROM AUTHOR]

In order to be innovative, libraries need to experiment and attempt new things. Part of this is the possibility of making mistakes and having failures along the way. Librarians can learn from these mistakes and failures and become better informed for future initiatives. However, like many organizations libraries are often risk-averse and do not reward experimentation and often mistakes and failures are looked on negatively. This can lead to less innovation and less learning – both on the individual and on the organizational level. Library leaders should encourage experimentation and understand that in order to be innovative, mistakes will be made and some initiatives will not be successful Making mistakes and having failures should not automatically be seen as a negative as long as they are used as leaning opportunities. By making mistakes, librarians can learn and grow. With this gained knowledge they, and their libraries, can be brought closer to success in the future. [ABSTRACT FROM AUTHOR]

This paper focuses on the possibility to identify via technical, verbal, and visual characteristics of the digital text, the authenticity or fictitiousness of Facebook profiles. It also attempts to shed light on the different motives behind the creation of fake profiles. The cases analyzed in this paper, through qualitative content analysis, emphasize the significance of the profile's authenticity in the eyes of Facebook users. The findings help distinguish between a fictitious identity and a "stolen" one. The findings also indicate that there are different types of fake profiles, and that these can be derived from a variety of motives ranging from business promotion to personal needs. The study concludes that there are a number of visual, verbal and interactive components that make it possible to assess the degree of authenticity or fictitiousness of a given profile. First, the content filled in the fields: personal details, the type of information that the profile owner chooses to share or keep discreet, the type of images and the extent to which they are used. Second, the degree of activity in the profile: the number of friends and the frequency of activity, such as being tagged in photos. Also, the study reveals that users have their own thoughts concerning what an authentic profile is, and they seek to create profiles that do not necessarily meet Facebook's narrow "authenticity" criteria. [ABSTRACT FROM AUTHOR]