Effects of temperature and thermal cycles on the mechanical properties of expanded polystyrene foam

Understanding the effects of high temperature and thermal cycles on the mechanical properties of expanded polystyrene (EPS) foam is critical for its use in sandwich panels. This paper presents an experimental investigation of these effects in typical environmental conditions that exist in construction applications. A total of 117 small specimens were cut from metal-faced sandwich panels with EPS core and were exposed to different numbers of thermal cycles and/or sustained high temperatures. The specimens were then loaded under compression, tension, and four-point bending for evaluating the degradation of the mechanical properties of the foam. The thermal cycles reflect typical surface temperature during daily summer conditions, with a period of 24 h each and with a temperature varying between 24°C to 80°C. The results show that the modulus of elasticity of EPS foam in compression reduced by about 38% after exposure to thermal cycles for 45 days, whereas the tensile and shear moduli reduced by about 5.7% and 13.8%, respectively. Exposure to sustained high temperature after thermal cycles led to larger degradation of the elastic and shear moduli in the range of 38%–50%. These degradations can lead to early failures in applications that rely on the EPS foam as a structural component like in insulating sandwich panels.

Neoliberal failures and the managerial takeover of governance

The history of neoliberalism is a messy attempt to turn theory into practice. Neoliberals struggled with their plans to implement flagship policies of monetarism, fiscal prudence, and public sector privatisation. Yet, inflation was still cut, welfare slashed, and the public sector ‘marketised’. Existing literature often interprets this as neoliberalism ‘failing-forward’, achieving policy goals by whatever means necessary and at great social cost. Often overlooked in this narrative is how far actually existing neoliberalism strayed from the original designs of public choice theorists and neoliberal ideologues. By examining the history of the Thatcher government's public sector reforms, we demonstrate how neoliberal plans for marketisation ran aground, forcing neoliberal governments to turn to an approach of Managed Competition that owed more to practices of postwar planning born in Cold War US than neoliberal theory. Rather than impose a market-like transformation of the public sector, Managed Competition systematically empowered top managers and turned governance into a managerial process; two developments that ran directly against core precepts of neoliberalism. The history of these early failures and adjustments provides vital insights into the politics of managerial governance in the neoliberal era.

Factors Associated With Early Failure of The Femoral Neck System (FNS) in Patients With Femoral Neck Fractures

BackgroundThe femoral neck system (FNS) is a novel internal fixation system for the treatment of femoral neck fractures (FNFs). However, there is a paucity of literature looking at the factors associated with early failure of the FNS (EFFNS) in patients with FNFs. In this study, we aimed to investigate the prevalence of EFFNS and identify risk factors for EFFNS in patients with FNFs.MethodsWe retrospectively analysed 62 patients who presented with intracapsular neck femur fractures and underwent FNS fixation between 2019 and 2021. Demographic, clinical characteristics and radiographic features are described. Multifactor logistic regression analysis was used to analyse the different influencing factors.ResultsOf the 62 FNFs, 10 patients (16.1%) developed early failures after FNS fixation, including 6 cases of severe femoral neck shortening, 1 case of avascular necrosis of the femoral head, 1 case of nonunion, and 2 cases of screw-out. In the failure group, all patients were younger than 65 years old. The proportion was significantly higher than the 59.6% in the healing group (P = 0.012). However, we found that Garden classification (P = 0.464) and age (P = 0.128) were not statistically significant risk factors for EFFNS. ConclusionsOur study demonstrated that age was an important factor influencing EFFNS. However, we cannot determine whether age and Garden classification are independent risk factors for EFFNS in the treatment of FNFs.Trial registration: ChiCTR2100051360. Registered on 21 September, 2021. https://www.chictr.org.cn/index.aspx.

Temperature Cycling Study of Aerosol-Jet Printed Conductive Silver Traces in Printed Electronics

Aerosol-Jet Printing (AJP) provides a new method for electronic component manufacturing. Understanding the reliability of electronics printed using the AJP process is essential to take full advantage of this technology and realize its industrial potential. In the current study, we have designed and tested AJP printed samples and conducted failure analysis of those samples that have exhibited early failures. Failures first occurred in the short traces that connect the main traces to the silver pads, due to local stress-raisers caused by local geometric features in the printing geometry. Thermal-Mechanical Finite-Element-Modeling (FEM) has been performed to analyze the cyclic history of thermo-mechanical stress distribution and plastic strain distribution.

Non- Carious Cervical Lesions: A Review

Non-carious cervical lesions (NCCL) are characterized by a loss of hard dental tissue near the cement-enamel-junction. Commonly, their shape is like a wedge with the apex pointing inwards. Other times, they appear as regular depressions, like a dome or a cup. Their etiology seems to be related to different factors: hexogen and endogen acids, mechanical abrasive action, tooth flexion under axial and non-axial loads. Moreover, it seems that a fundamental role is ascribable to tooth bending phenomena due to the strength components parallel or oblique to the occlusal level, which occur during the normal function as well as during Para functions. The frequent therapeutic failures are probably due to the same factors causing the onset of the original lesion. Several materials have been proposed to restore NCCL: amalgam (abandoned) glass-ionomer cements, composers, and composite resins. Early failures of these restorations have often been reported in the literature, probably due to the same factors which originally caused the lesions. Further investigations are required to determine more reliable restorative therapies.

Is Penicillin Allergy a Risk Factor for Early Dental Implant Failure? A Systematic Review

The prescription of preventive antibiotics in dental implant treatments reduces the incidence of early failures. This study has focused mainly on the influence of amoxicillin, which is contraindicated in penicillin-allergic patients. The present systematic review aimed to determine whether penicillin-allergic patients have a higher risk of implant failure compared to non-allergic patients. An electronic search was performed on Medline and Web of Science using the following MeSH terms: (penicillin allergy OR clindamycin OR erythromycin OR azithromycin OR metronidazole) AND (dental implant OR dental implant failure OR dental implant complications). The criteria employed were those described in the PRISMA® Declaration. Only five articles were included that analyzed the failure rates of implants placed in penicillin-allergic patients who were prescribed clindamycin compared to non-allergic patients who were prescribed amoxicillin. With the limitations of this study, it is not possible to state that penicillin allergy per se constitutes a risk factor for early dental implant failure as most of the studies included self-reported allergic patients. Clindamycin has been associated with a significantly elevated risk of failure and an up to six times increased risk of infection. Immediate implants also have a 5.7 to 10 times higher risk of failure.

Factors associated with early and late digital revascularization and replantation failure: A retrospective cohort study

Factors associated with failure of digital revascularization and replantation procedures have been well characterized, but studies have not investigated failures occurring beyond the early postoperative period. A single-centre retrospective chart review included 284 patients (434 digits) who underwent digital revascularization or replantation. Patient-, injury- and surgery-related characteristics were compared among successful procedures, digits that failed while in hospital (early failure), and initially viable digits that failed after hospital discharge (late failure). Overall, 202 patients had successful procedures (71%). There were 51 early failures (18%) and 31 late failures (11%). Crush injuries and vein grafting were associated with early failure only. Complete amputations and leeching were strongly associated with both early and late failure. This study revealed that a substantial proportion of initially viable digits fail after discharge from hospital. Patients with signs of venous congestion may benefit from longer observation periods in hospital to avoid late failure. Level of evidence: IV

Monitoring and Calibration of Long Term Mooring System Design Assumptions Through Use of AIS and Weather Data

This paper outlines an approach on how to improve the mooring integrity of existing long term mooring systems by using existing and commercially available data. It will be demonstrated how the use of AIS and hindcast weather data can be used to increase understanding of mooring systems and to monitor and quantify gaps between "as-designed", "as-installed" and "as-is" of a long term mooring system. Long term moored units have traditionally suffered from many early failures, caused by damages and errors introduced in the installation phase, and costly and unnecessary "late in life" failures. A fact rated high on the agenda of the underwriters. Numerous papers have been written on this topic, but it is only in recent years the industry have started to ensure that systems are inspected to a sufficient degree with respect to the physical condition, taking these learnings into account. However, the second important element, the calibration of the mooring analysis vs. actual vessel and mooring system behavior/performance, have not yet gotten the attention required. Deviations from the intended design are introduced in the installation phase of a mooring system. In addition, the design assumptions will never be fully accurate. The gap between the design assumptions and the actual system will increase over time, and the industry today do not focus on mapping and quantifying the effect of this gap sufficiently. The described method explains how one can introduce a pro-active approach, without installing onboard equipment, but rather utilizing algorithms on existing data and design documentation. This paper focuses on the use of AIS data in combination with historic weather/environmental data and seek to demonstrate how this low-cost method can provide useful information with respect to the mooring system. To emphasize the mapped importance of such calibrations, the July 2021 Edition of the in-service DNV Class Rules, DNVGL-OS-0300, formally introduces requirements to calibration of design assumptions of long term mooring units through use of survey data, service history and actual mooring system behavior in order to ensure a unit's mooring system condition and performance is known in light of the original design assumptions.

Comprehensive Approach to Tackle Systemic Failure in Gas Lift Valves in Pre Salt Wells

This work describes a comprehensive approach to tackle systemic failure in gas lift valves in pre-salt wells. Failure analyses in gas lift valves were performed after unexpected early failures leading to tubing-annulus communication. Understanding the root causes of this problem generates value for assets, increasing equipment life, preventing unnecessary workover, and reducing costs. Suspect failed valves are systematically removed from the wells, usually by slick-line workovers, and brought to an onshore workshop, where their integrity and mechanical functionality can be analyzed. The valve's run life, equipment model and manufacturer, annular fluid, flow through the gas lift valve, operational pressure and temperature, composition of reservoir fluids and solids deposition were verified. Besides, transient simulations were carried out to provide insights on the root causes of the failure. Also, a good understanding on how each valve works, including its engineering design, was necessary to thoroughly understand the failure process. The study of gas-lift injection valves early failure in pre-salt wells have been an excellent way to understand the life cycle of production wells before the need to start lift gas injection. That leads to a comprehensive understanding about the effects of the fluids left in annulus and have supported Petrobras in most effectively managing of well integrity and workover costs. The analysis incorporates the impact of oil production, water cut, completion type, annular fluid composition, anti-scaling fluid injection (composition and efficiency) and the differential pressure between the tubing of the annulus in the valve failure model. The composition of the deposit found inside the valves and the production history of the well were essential to assemble the puzzle of how the failure mechanism works. With the acquired knowledge, it has been possible to apply barriers to avoid future events of unwanted tubing-annulus communication arising from gas-lift valve failures. This article provides a methodology and examples for a most effective understanding of the gas-lift valves failure mechanisms and their root causes, which proved to be a valuable tool for the artificial lift design and for the planning of well operations. That has contributed to maximize equipment life, cost reduction and, at last, generating value for the company.

Learning to Predict Proliferation

How effective are states at assessing and predicting the nuclear intentions of foreign countries? Drawing on close to 200 US assessments of foreign countries’ proliferation intentions between 1957 and 1966, this research note finds that close to 80 percent of testable US assessments were correct and that they shifted from highly inaccurate in the late 1950s to highly accurate in the 1960s. Based on quantitative and qualitative analysis, I conclude that learning from early failures led the intelligence community to achieve higher accuracy.