Detailed Categories Research Articles

Fatigue strength of repaired cracks in base material of high strength steels

Fatigue crack formation is an inevitable issue for welded steel structures subjected to cyclic loading. Accordingly, repair of the fatigue crack in welded steel structures is unavoidable to prolong fatigue life. However, there is limited knowledge available about the procedure to be adopted for the repair and the life extension to be expected after the repair. The current paper is focused on the effects of the repaired an artificial crack in the base material of S690 and S890 high strength rolled steels on the fatigue strength of the material. An artificial crack was created in the middle of the plate test specimens by spark machining and subsequently, the crack was repaired by using the FCAW (flux-cored arc welding) process. The repaired specimens were tested in a four point bending test rig with a constant amplitude loading for creating a uniform bending moment at the weld region such that the weld cap to be exposed to tensile stresses. The test results show that most of the fatigue cracks initiated at the start-stop points of the weld cap and the fatigue crack initiation life of the specimens occupy approximately 45% of the total fatigue life. The statistical analysis of the test results revealed that the characteristic fatigue strength of the repaired specimens is very close to the detail category 160 of EN 1993-1-9 [5].

RETRACTED: A Study on the Fatigue Behavior of Hot Dip Galvanized Steel Connections

Retracted article: The effect of a galvanizing coating on the fatigue strength of S355 structural steel is analyzed in detail showing that the decrease of the fatigue life is very limited if compared with that of uncoated joints and the results are in good agreement with Eurocode detail category, without substantial reductions. The procedure for the preparation of the specimens is systematically described in this note providing a useful tool for engineers involved in similar practical applications. The results are compared with previous data from notched galvanized specimens weakened by a central hole and not treated specimens characterized by the same geometry.

Behaviour of several fatigue prone bridge details

Three fatigue welded bridge joints analysed in this work are the alternative details of the bottom flange connection. This construction detail is mainly used for the erection connection for steel and composite bridges. If applied in the place, where live load is significant, the fatigue becomes the main design criterion. The detail category is thus very important factor. The aim of this paper is to analyse the possibilities of the improving the behaviour of this detail, by various methods. First solution is to modify the shape of the cope hole to the elliptic shape. Second option is to use the “Olemutz” fully welded detail. This detail is often used in bridge designing despite there is no exact information about the fatigue category, and doubts of the performance exists. “Olemutz” is a long web plate slit that is filled by the double bevel weld after the execution of the bottom flange weld. The last detail is the elliptic cope hole filled by the plate-cap welded into an empty hole. The geometry is the same, as in the first case. The conclusion of the numerical analysis and the pilot fatigue experiments is discussed with several practical recommendations for designing.

09.17: Fatigue life of marked steel components

ABSTRACTSteel components have to be identifiable and traceable during the whole manufacturing chain. The choice of the identification method is not specified consistently in international rules and standards. The European standard for the execution of steel structures EN 1090‐2 specifies that the use of durable marks may not result in producing damages without saying which damages are meant. Hard stamped marks are only permitted for steel grades up to S355 and only in areas where no effect on the fatigue life is expected. Otherwise the use of soft stamps should be verified. In other international standards hard stamped marks are explicitly required. These contradictions should be resolved.In terms of durability and liability, markings should be resistant against particular manufacturing processes such as sandblasting, hot‐dip galvanizing or coating. For this reason, the following marking methods are used in practical applications: hard stamping, scribing, plasma marking and needling.Nowadays the machinery manufacturers have developed machines in which the marking process can be automatically integrated in the manufacturing process of steel components so that manual layout scribing is not required anymore and components can be marked on the fly. However, the effect of the installed notch due to the marking process on the fatigue strength of the components has not been investigated yet. As a result, a classification of the resulting notched details according to the European detail categories of EN 1993‐1‐9 is in principle not possible.For these reasons, the influence of durable marking methods on the fatigue strength of steel components needs to be clarified by experimental fatigue tests and numerical calculations which have been performed at the Institute for Metal and Lightweight Structures of the University of Duisburg‐Essen. Within these investigations the different marking methods hard stamped, scribed, plasma marked and needled as well as unmarked structural details have been examined. The experimental investigations have been carried out considering three different steel plate thicknesses 15 mm, 25 mm and 40 mm and two different steel grades S355J2 and S460N.As expected the marked specimens show a decrease of the loading cycles until failure even though there are differences in fatigue life due to the different markings and their characteristic notch geometries.

Experimental Study on Fatigue Behaviour of Shot-Peened Open-Hole Steel Plates.

This paper presents an experimental study on the fatigue behaviour of shot-peened open-hole plates with Q345 steel. The beneficial effects induced by shot peening on the fatigue life improvement are highlighted. The characteristic fatigue crack initiation and propagation modes of open-hole details under fatigue loading are revealed. The surface hardening effect brought by the shot peening is analyzed from the aspects of in-depth micro-hardness and compressive residual stress. The fatigue life results are evaluated and related design suggestions are made as a comparison with codified detail categories. In particular, a fracture mechanics theory-based method is proposed and demonstrated its validity in predicting the fatigue life of studied shot-peened open-hole details.

Effect of hot dip galvanization on the fatigue strength of steel bolted connections

Hot dip galvanized steel bolted joints has been tested under fatigue loading to evaluate the effect of galvanizing coating on the fatigue strength of S355 structural steel. The experimental results showed that the decrease of the fatigue life of coated specimens in comparison with that of uncoated joints is very limited and the results are in good agreement with Eurocode detail category, without substantial reductions. The procedure for coating and preparation of the bolted joints is described in detail in this paper providing a useful tool for engineers involved in similar practical applications. The experimental results are compared with the previously published data on central hole notched galvanized and not treated specimens characterized by the same geometry.

A physically-based model of long-term food demand

Reducing hunger while staying within planetary boundaries of pollution, land use and fresh water use is one of the most urgent sustainable development goals. It is imperative to understand future food demand, the agricultural system, and the interactions with other natural and human systems. Studying such interactions in the long-term future is often done with Integrated Assessment Modelling. In this paper we develop a new food demand model to make projections several decades ahead, having 46 detailed food categories and population segmented by income and urban vs rural. The core of our model is a set of relationships between income and dietary patterns, with differences between regions and income inequalities within a region. Hereby we take a different, more long-term-oriented approach than elasticity-based macro-economic models (Computable General Equilibrium (CGE) and Partial Equilibrium (PE) models). The physical and detailed nature of our model allows for fine-grained scenario exploration. We first apply the model to the newly developed Shared Socio-economic Pathways (SSP) scenarios, and then to additional sustainable development scenarios of food waste reduction and dietary change. We conclude that total demand for crops and grass could increase roughly 35–165% between 2010 and 2100, that this future demand growth can be tempered more effectively by replacing animal products than by reducing food waste, and that income-based consumption inequality persists and is a contributing factor to our estimate that 270 million people could still be undernourished in 2050.

의무기록 전공 대학생의 회복탄력성 군집에 따른 학업소진, 진로준비행동 등의 융합적 차이

이 연구는 의무기록 전공 대학생 대상 회복탄력성의 군집별로 학업소진, 진로준비행동 및 일반적 특성의 융합적 차이를 파악하고 특성에 따른 개선방안을 도출하기 위한 것이다. 의무기록 전공 대학생을 대상으로 자기기 입식 설문을 실시하여 최종 168건에 대해 분석을 실시하였다. 연구결과, 회복탄력성의 3가지 세부 영역에 따라 군집분석한 결과 2개의 군집으로 분류되었다. 군집1은 세 영역 모두 한국인 평균 이상인 보통수준의 집단이었고, 군집2는 세 영역 모두 한국인 평균보다 낮은 군이었다. 군집1은 진로준비행동, 취미 유, 주관적 건강상태가 좋은 편, 외향적 성격, 성적 상, 대학생활 만족, 전공 만족한 비율이 군집2보다 높았고, 학업소진은 더 낮아 군집 간 차이를 보였다. 따라서 군집2에 속하는 집단에 초점을 맞춘 긍정성 강화 교육을 통해 전체 회복탄력성을 높일 수 있을 것이다. The purpose of this study is to find convergence differences of academic burnout, career preparation behavior, and general characteristics of the students majoring in medical records according to each cluster of resilience, and draw a proper improvement plan. A self-administered questionnaire survey had been conducted and a total of 168 copies were analyzed. As a results Cluster analysis was conducted on three detailed categories of resilience and was classified into two clusters. Cluster1 was a group that had points higher than the average points of Korean in each one of three categories. Cluster2 had all of which were lower points than that. Cluster1 had higher points than cluster2 in terms of career preparation behavior, hobby, subjectively good health condition, extroverted personality, good academic records, satisfaction with school life, and study satisfaction ratio, but had lower points than cluster2 in terms of academic burnout. Therefore, positiveness enhancement education focused on cluster2 will improve total group resilience.

An Analysis of Job and Wage Growth in the Telecom/Tech Sector

This paper examines job growth at leading tech/telecom firms. We compare them to leading industrial firms, both in the first half of the 20th century and in the post-war era, and show that they have similar employment trajectories. Then we consider wage and industrial structure trends. We find that real wages in the tech/telecom sector are higher and rising faster than in the physical sector. To correct for composition effects, we examine detailed occupational categories, and find that for middle-skill occupations such as sales and office support, the tech/telecom sector has significantly higher wages than the physical sector.

Conflict of Law Regulation of Marital and Family Relations in International Private Law in Russia

Russian conflict of law rules determining choice of law applicable to marital relations related to foreignlegislations came into force in 1995 and in force for 20 years. Within Russian legal doctrine the area hasbeen researched in detail. Nevertheless, the analysis of conflict of law rules specified in the Family Codeof Russian Federation remains relevant due to a large-scale reform of the norms of international privatelaw in the Civil Code of the Russian Federation and the trends which are present in legislative regulationof international family relations in other countries. Chapter 7 of the Family Code The Application of FamilyLegislation to Family Relations with the Participation of Foreign Citizens and Persons without Citizenshipprovides a detailed system of rules determining competent law to regulate majour family relations. Mostconnecting factors are of bilateral nature and provides for the application of foreign laws. However, forthe past 20 years international family relations experienced new regulation, which is evident in nationalcodifications of International private law and in the European Union law. The current legislator extendsthe limits of autonomy of the parties in marital relations on the choice of applicable law, sets special connectingfactors as to cohabitation and partnership, fixes detailed and differentiated choice of law rule. Thepaper concludes that Russian conflict of laws on international marital relations approved more than twodecades ago requires significant update. The update is relevant to maximum transparency of volumesof conflict of law rules to make a more differentiated approach to marital relations, more detailed and arrangedin categories connecting factors targeting the most correct determining the law, closest to the relationand making a decision optimally meeting specific circumstances of cases, broadening the possibilityof the choice of applicable law by the parties on the issues of dissolution of marriage and family propertyrelations. All the problems concerning children applying law the most favourable for child should dominatein conflict of laws doctrine in such circumstances.

How does democratization affect the composition of government expenditure?

This study examines the effects of democratization on the size and composition of government expenditure using the data of 125 countries between 1972 and 2010 at most. Specifically, we focus not only on the total expenditure but also on the composition, and we employ dichotomous indices of political regimes rather than score indices. Moreover, we construct instruments for democratization based on the democratization wave and conduct an instrumental variables estimation to address endogeneity problems. Our results show that while democratization does not have a significant impact on total expenditure, it increases expenditure on health. Democratization decreases expenditure on defense, although the result of the instrumental variables estimation is not significant. Furthermore, considering the time-varying effect of democratization, defense expenditure starts decreasing immediately after a regime change and health expenditure increases in the medium and long run, while they do not significantly vary before a regime change. Thus, while focusing only on total expenditure does not uncover the effects of democratization, considering detailed categories of government expenditure enables us to understand how democratization changes governments’ behaviors.

Utilising aversive conditioning to manage the behaviour of K’gari (Fraser Island) dingoes (Canis dingo)

K’gari (Fraser Island) offers a rare opportunity for people to observe and encounter wild dingoes. Occasionally, however, such encounters can entail dingoes acting in a threatening or aggressive manner towards people, resulting in human injury and, in one tragic case, death. A suite of approaches aimed at minimising the risk to human safety posed by dingoes have been implemented on the island, including fencing, island-wide warning signage, and regulations against feeding. Despite such measures, negative encounters continue, and in cases where dingoes are deemed to pose an unacceptable risk, they are usually destroyed. In searching for non-lethal management alternatives, attempts have been made to modify undesirable dingo behaviour through aversive conditioning, but results to date have either been mixed or largely disappointing. Here we review a wide array of research that has utilised aversive stimuli in an effort to modify and manage the behaviour of wild animals, with a particular focus on related predators such as coyotes and wolves. We identified eight major categories of experimental research: conditioned taste aversion/avoidance (CTA), electric fencing, fladry, chemical repellents, fear-evoking stimuli, physical repellents, aversive collars/devices and hard release procedures. We then outline each of these categories in more detail, complete with pertinent examples of successes and failures as well as advantages and disadvantages. We conclude that some approaches offer promise within three main areas of incident mitigation experimentation: dingo exclusion (e.g. electric fencing), personal protection (mild chemical irritant sprays, sturdy umbrellas) and remedial aversive conditioning (e.g. shock collars). Other approaches, such as CTA and sublethal projectiles are not recommended. Like any approach, aversive conditioning is not a panacea, but it does offer promise in filling gaps in current management and as an alternative to lethal control.

Fatigue testing of a bolted connection for buried flexible steel culverts

A fatigue assessment of steel structures based on the safe life approach requires a detail category representing the fatigue strength. For flexible culverts there are no matching details in the gov ...

Mechanical behaviour of hot dip galvanized steel connection under cyclic loading

Abstract: This short technical note summarizes some recent data from hot dip galvanized steel bolted connections under fatigue loading. In particular the effect of a galvanizing coating on the fatigue strength of S355 structural steel is analyzed in detail showing that the decrease of the fatigue life is very limited if compared with that of uncoated joints and the results are in good agreement with Eurocode detail category, without substantial reductions. The procedure for the preparation of the specimens is systematically described in this note providing a useful tool for engineers involved in similar practical applications. The results are compared with previous data from notched galvanized specimens weakened by a central hole and not treated specimens characterized by the same geometry.

A framework for the environmental, health and safety hazard assessment for amine-based post combustion CO2 capture

Given the environmental concerns driving process developments and considering the size and scale of potential application of post combustion capture (PCC), it is important to fully understand process hazards. In this work we present an environmental, health and safety (EHS) hazard assessment framework for screening and comparing amine based PCC options. A multi-criteria assessment compares the performance of 7m Monoethanolamine (MEA), 4m Diethanolamine (DEA), 10m Diglycolamine (DGA), 8m Piperazine (PZ) and a blend of 7m Methyldiethanolamine (MDEA) with 2m PZ under a set of different process conditions. The EHS assessment takes into account varying circulating volumes, process conditions and potential for solvent degradation. The EHS assessment is also compared with operating costs and life cycle assessment (LCA) metrics. The EHS assessment is carried out on two levels. The first is less data intensive and provides a unified score that can be used to compare and screen process alternatives, while the second level studies the contribution of individual degradation products to different EHS hazard categories in detail. Results of the parametric study show that lean loading is an influential factor in determining first level EHS scores, process costs and environmental impacts and a trade-off is observed between EHS and LCA scores for some of the solvents. In the second level EHS assessment, the parent amine heavily influences most mass dependent hazard categories such as the fire/explosion, acute toxicity and air mediated effects category. Heat stable salts affect the solid waste category. Most degradation products are considered corrosive or irritant and therefore feature strongly in that category in addition to the parent amine. The second level EHS assessment is complemented with workplace exposure analysis to ensure the compliance with workplace threshold limits. Nitrosamines stand out for acute and chronic toxicity effects and are therefore used as an example to demonstrate the workplace exposure. Workplace amines and nitrosamine concentrations are estimated to assess long and potential short term worker exposure as a result of gas leakages and spills respectively. Indoor ventilation rates are inadequate to keep workplace amine and nitrosamine concentrations below the recommended guidelines. To reduce short term exposure effects, a steady state liquid nitrosamine concentration lower than 13.7mM is required. The results of the parametric study show that changing process conditions can lower nitrosamine concentrations, but can also shift the contribution of the parent amine and degradation products of the other hazard categories and affect LCA metrics. The sensitivity of the EHS and LCA results to model assumptions and conditions are tested by varying inlet NOx, expected aerosols and solvent degradation levels. Low NOx levels in the flue gas are required for PZ and MDEA-PZ systems to meet the nitrosamine concentration thresholds for environmental and health concerns. This study also highlights the need to consider hazard effects during early process design phases, identifies degradation related data gaps and critical process parameters towards more environmentally benign PCC design.

Are publicly insured children less likely to be admitted to hospital than the privately insured (and does it matter)?

There is continuing controversy about the extent to which publicly insured children are treated differently than privately insured children, and whether differences in treatment matter. We show that on average, hospitals are less likely to admit publicly insured children than privately insured children who present at the ER and the gap grows during high flu weeks, when hospital beds are in high demand. This pattern is present even after controlling for detailed diagnostic categories and hospital fixed effects, but does not appear to have any effect on measurable health outcomes such as repeat ER visits and future hospitalizations. Hence, our results raise the possibility that instead of too few publicly insured children being admitted during high flu weeks, there are too many publicly and privately insured children being admitted most of the time.

Mapping invasive alien Acacia dealbata Link using ASTER multispectral imagery: a case study in central-eastern of Portugal

Aim of the study: Acacia dealbata is an alien invasive species that is widely spread in Portugal. The main goal of this study was to produce an accurate and detailed map for this invasive species using ASTER multispectral imagery.Area of study: The central-eastern zone of Portugal was used as study area. This whole area is represented in an ASTER scene covering about 321.1 x 103 ha.Material and methods: ASTER imagery of two dates (flowering season and dry season) were classified by applying three supervised classifiers (Maximum Likelihood, Support Vector Machine and Artificial Neural Networks) to five different land cover classifications (from most generic to most detailed land cover categories). The spectral separability of the land cover categories was analyzed and the accuracy of the 30 produced maps compared.Main results: The highest classification accuracy for acacia mapping was obtained using the flowering season imagery, the Maximum Likelihood classifier and the most detailed land cover classification (overall accuracy of 86%; Kappa statistics of 85%; acacia class Kappa statistics of 100%). As a result, the area occupied by acacia was estimated to be approximated 24,770 ha (i.e. 8% of the study area).Research highlights: The methodology explored proved to be a cost-effective solution for acacia mapping in central-eastern of Portugal. The obtained map enables a more accurate and detailed identification of this species’ invaded areas due to its spatial resolution (minimum mapping unit of 0.02 ha) providing a substantial improvement comparably to the existent national land cover maps to support monitoring and control activities.Keywords: remote sensing; invasive alien species; land cover mapping; vegetation mapping.

Patterns of Smoking and Snus Use in Sweden: Implications for Public Health

There has been concern that the availability of alternative less harmful forms of nicotine might inhibit smoking cessation and/or encourage those who would not otherwise have smoked to do so. The plausibility of such effects can be best assessed by looking at population trends in use of smoking in relation to alternatives. This paper looks at the relationships between snus use and smoking in Sweden. Analyses are based on a data set for the period January 2003 to February 2011 from a long-term study covering nationally representative samples of the Swedish population aged 18–79, with a total study population of 60,675 individuals. Questionnaires made it possible to identify detailed tobacco use categories and use trajectories. The results showed that uptake of snus use is much more common in males than females. Those who began daily tobacco use using snus were much less likely to subsequently take up smoking than those who had not, both among males (17.6% vs. 45.9%), and females (8.2% vs. 40.2%). Further, among those who started using snus after starting as smokers, 76.3% of men and 71.6% of women had stopped smoking completely, including 31.5% of the men and 28.6% of the women who had quit all forms of tobacco. Indeed, those who were primary snus users were also more likely to have quit altogether than those who only ever smoked. Snus was also reported as the most common smoking cessation aid among men and yielded higher success rates than nicotine replacement therapy and other alternatives. As conclusions, snus has both contributed to decreasing initiation of smoking and, when used subsequent to smoking, appears to facilitate smoking cessation. All these effects suggest that the availability and use of snus has been a major factor behind Sweden’s record-low prevalence of smoking and the lowest level of tobacco-related mortality among men in Europe.

Multilevel Small-Area Estimation of Multiple Cigarette Smoking Status Categories Using the 2012 Behavioral Risk Factor Surveillance System.

Smoking is the leading preventable cause of death; however, small-area estimates for detailed smoking status are limited. We developed multilevel small-area estimate mixed models to generate county-level estimates for six smoking status categories: current, some days, every day, former, ever, and never. Using 2012 Behavioral Risk Factor Surveillance System (BRFSS) data (our sample size = 405,233 persons), we constructed and fitted a series of multilevel logistic regression models and applied them to the U.S. Census population to generate county-level prevalence estimates. We mapped the estimates by sex and aggregated them into state and national estimates. We conducted comparisons for internal consistency with BRFSS states' estimates using Pearson correlation coefficients, and external validation with the 2012 National Health Interview Survey current smoking prevalence. Correlation coefficients ranged from 0.908 to 0.982, indicating high internal consistency. External validation indicated complete agreement (prevalence = 18.06%). We found large variations in current and former smoking status between and within states and by sex. County prevalence of former smokers was highest among men in the Northeast, North, and West. Utah consistently had the lowest smoking prevalence. Our models, which include demographic and geographic characteristics, provide reliable estimates that can be applied to multiple category outcomes and any demographic group. County and state estimates may help understand the variation in smoking prevalence in the United States and provide information for control and prevention. Detailed county and state smoking category estimates can help identify areas in need of tobacco control and prevention and potentially allow planning for health care. Cancer Epidemiol Biomarkers Prev; 25(10); 1402-10. ©2016 AACR.

Highlights of This Issue

Kennedy and colleagues reported on the establishment of a web-based Cancer Epidemiology Descriptive Cohort Database (CEDCD) with goals to enhance awareness of resources, facilitate interdisciplinary research collaborations, and support existing cohorts for the study of cancer-related outcomes. The CEDCD includes data from 46 cohorts representing more than 6.5 million individuals. Genotyping has been performed by 67% of the cohorts, while 46% have performed whole genome or exome sequencing in subsets of enrolled individuals. The CEDCD assembles detailed descriptive information on a large number of cancer cohorts in a searchable database.Asian Americans are the fastest growing U.S. population, yet trends and patterns in the mortality burden of cancer among Asian American ethnic groups have not been documented. Thompson and colleagues reported on rates, standardized mortality ratios, and modeled trends in cancer-related mortality in different Asian American ethnicities from 2003 to 2011. Stomach and liver cancer mortality was very high, particularly among Chinese, Koreans, and Vietnamese, for whom these two cancer types combined accounted for 15–25% of cancer deaths. In Asian American women, lung cancer was a leading cause of death.Physician communication about human papillomavirus (HPV) vaccine is a key determinant of uptake. Malo and colleagues sought to identify messages that help motivate HPV vaccination by surveying national samples of parents of adolescents and primary care physicians. The highest proportion of parents and physicians found this brief message to be persuasive: “I strongly believe in the importance of this cancer-preventing vaccine for [child's name].” Parents' endorsement did not vary by race/ethnicity, education, child age, or child sex. The findings support physicians' use of these messages with parents to help motivate uptake of this important cancer-preventing vaccine.Berkowitz and colleagues developed multilevel small area estimate models to generate county-level estimates for six smoking status categories. The authors constructed and fitted a series of multilevel logistic regression models and applied them to the U.S. Census population to generate county-level prevalence estimates. They found large variations in current and former smoking status between and within states and by sex. County prevalence of former smokers was highest among men in the Northeast, North, and West. Utah consistently had the lowest smoking prevalence. These detailed county and state smoking category estimates can help identify areas in need of tobacco control and prevention.