Wave-structure interaction. The effective prediction of wave-in-deck loads

The safe and efficient design of many offshore structures is critically dependent on the accurate prediction of the applied wave loads. In analysing these loads, the contribution arising at or close to the instantaneous water surface is particularly significant. The reasons for this relate to moment arm effects leading to large contributions to the total overturning moment, to the uncertainty in the predicted kinematics and hence the applied loads and, perhaps most significantly, to the occurrence of wave-in-deck loads. The imposition of ever more stringent design conditions implies that the prediction of wave-in-deck loads (leading to a step change in the applied loads) is a major issue for both the design of new structures and the reassessment of existing structures. In the case of new structures, design procedures seek to avoid the occurrence of wave-in-deck loads by attempting to maintain a sufficient air-gap; whilst for existing structures it is essential to understand the loads that may arise. In both cases, one must understand the nature of the incident waves and the subsequent wave-structure interaction. The present thesis is concerned with both modelling extreme ocean waves and their interaction with offshore structures; the ultimate aim being to predict the wave loads arising close to the water surface. Wave-structure interaction effects due to two different types of irregular incident waves are investigated. Focused wave events that simulate the largest waves in a sea state replicating extreme or `freak' waves are considered experimentally. These are compared to the largest crests generated in long random simulations and to numerical simulations using a Boundary Element Method (BEM). This is followed by an assessment of which wave events impose the largest loads and under what circumstances. This is achieved by considering the most critical wave crests expected in a storm with a given return probability, and quantifying the consequent wave loads on a range of model platforms of increasing complexity. First, the loading on various elements of a simple deck with no underlying structure is investigated; enabling the loads due to the incident waves when there is no prior wave-structure interaction to be determined. Next, the effect of different underlying columns is examined. The global wave-in-deck loads on a model deck with a jacket sub-structure are then investigated, and finally, the loads on both the deck and underlying columns of a model Gravity-Based-Structure (GBS) are quantified. At each stage the sensitivity of the loads to a range of wave conditions and deck parameters is revealed. Additionally, representative wave kinematics are compared to the measured loads and found to correlate well with standard slamming coefficients. Comparisons to other simple predictive methods currently used by industry are also made. This study has shown that the highest wave crest is not necessarily found at the centre of a nonlinear wave group. Indeed, an asymmetrical profile has been found to occur in steep random sea states, and can cause much larger wave-in-deck impact loads than a symmetrical profile of similar height. The incident wave profile has a massive effect on the measured loads; breaking waves just prior to overturning producing the largest loads. Finally, it has been shown that it is not always possible to avoid wave-in-deck impacts completely, especially for large volume structures that significantly alter the incident waves. Indeed, wave-structure interaction effects have been shown to cause substantial wave impact loads on the deck of a large volume structure at almost twice the maximum incident surface elevation

The Decline of Students Entering Engineering & Other Technical Fields in the United States

The United States is nearing an engineering crisis. The need for technical professionals is growing rapidly and universities are unable to meet the demand due to declining enrollment. Students are coming out of high school with little or no interest in technical fields, and the ones that do show interest are often lacking the math and science background required. Research has shown that a majority of students are not knowledgeable about engineering as a career option. Investigation is needed to learn how we can increase awareness of engineering and its value to the world. A pilot survey was developed and administered to students in both elementary and high school classes, to learn student opinions on the subject. Measures of the survey were as follows: 1) Student career aspirations. It was found that younger students often select careers which followed their parents’ footsteps, while older students selected careers in fields where they showed talent. 2) Feelings toward school subjects, mathematics and science in particular. The most common reason given for enjoying a subject was that it was “fun;” opinions of math and science declined as students grew older and found the classes “boring”. 3) General knowledge of engineering. Most students associated “engineering” to cars and trains via the word “engine,” only 15% could correctly described the field. This paper reviews already published writing on this issue, as well as development, administration, and results of the pilot survey

Descriptive Epidemiology of Non–Time-Loss Injuries in Collegiate and High School Student-Athletes

CONTEXT: Research on non-time-loss (NTL) injuries, which result in less than 24 hours of restriction from participation, is limited. OBJECTIVE: To describe the epidemiology of NTL injuries among collegiate and high school student-athletes. DESIGN: Descriptive epidemiology study. SETTING: Aggregate injury and exposure data collected from a convenience sample of National College Athletic Association varsity teams and 147 high schools in 26 states. PATIENTS OR OTHER PARTICIPANTS: Collegiate and high school student-athletes participating in men's and boys' baseball, basketball, football, lacrosse, soccer, and wrestling and women's and girls' basketball, field hockey, lacrosse, soccer, softball, and volleyball during the 2009-2010 through 2013-2014 and the 2011-2012 through 2013-2014 academic years, respectively, participated. Collegiate student-athletes participating in men's and women's ice hockey were also included. MAIN OUTCOME MEASURE(S): Injury data from the National Collegiate Athletic Association Injury Surveillance Program and the National Athletic Treatment, Injury and Outcomes Network were analyzed. Injury counts, rates per 1000 athlete-exposures (AEs), and rate ratios were reported with 95% confidence intervals (CIs). RESULTS: A total of 11 899 and 30 122 NTL injuries were reported in collegiate and high school student-athletes, respectively. The proportion of NTL injuries in high school student-athletes (80.3%) was 1.61 times greater than that of collegiate student-athletes (49.9%; 95% CI = 1.59, 1.63). The NTL injury rate in high school student-athletes (8.75/1000 athlete-exposures [AEs]) was 2.18 times greater than that of collegiate student-athletes (4.02/1000 AEs; 95% CI = 2.13, 2.22). Men's ice hockey (5.27/1000 AEs) and boys' football (11.94/1000 AEs) had the highest NTL injury rates among collegiate and high school athletes, respectively. Commonly injured body parts in collegiate and high school student-athletes were the hip/thigh/upper leg (17.5%) and hand/wrist (18.2%), respectively. At both levels, contusions, sprains, and strains were the most frequent diagnoses. Contact with another player was the most cited injury mechanism (college = 38.0%, high school = 46.3%). CONCLUSIONS: Non-time-loss injuries compose large proportions of collegiate and high school sports injuries. However, the NTL injury rate was higher in high school than in collegiate student-athletes. Tracking NTL injuries will help to better describe the breadth of injuries sustained by athletes and managed by athletic trainers

Creatieve Inspiratie Kalender

Een jaar inspiratie voor brede creativiteitsontwikkeling van leerlingen op de basisschoo

"What else to say?" – Primary health care in times of COVID-19 from the perspective of German general practitioners: an exploratory analysis of the open text field in the PRICOV-19 study

Background The international collaboration study PRICOV-19 –Primary Health Care in times of COVID-19 aims to assess the impact of the COVID-19 pandemic on the organisation of primary health care. The German part focuses on the subjective perceptions of general practitioners on primary health care and the impact of political measures during the second wave of the COVID-19 pandemic. Within this survey, the “open text field” of the questionnaire was utilised remarkably frequently and extensively by the respondents. It became clear that the content that was named needed to be analysed in an exploratory manner. Accordingly, this paper addresses the following question: What preoccupies general practitioners in Germany during COVID-19 that we have not yet asked them enough? Methods The data collection took place throughout Germany from 01.02.2021 to 28.02.2021with a quantitative online questionnaire consisting of 53 items arranged across six topics as well as an “open text field” for further comments. The questionnaire’s open text field was analysed following the premises of the qualitative content analysis. Results The topics discussed by the respondents were: insufficient support from health policies, not being prioritised and involved in the vaccination strategy, feeling insufficient prepared, that infrastructural changes and financial concerns threatened the practice, and perceiving the own role as important, as well as that health policies affected the wellbeing of the respondents. One of the main points was the way general practitioners were not sufficiently acknowledged for their contribution to ensuring high-quality care during the pandemic. Discussion German general practitioners perceived their work and role as highly relevant during the COVID-19 pandemic. In controversy with their perception, they described political conditions in which they were the ones who contributed significantly to the fight against the pandemic but were not given enough recognition

Epidemiologic Measures for Quantifying the Incidence of Concussion in National Collegiate Athletic Association Sports

Injury rates compare the relative frequency of sport-related concussions across groups. However, they may not be intuitive to policy makers, parents, or coaches in understanding the likelihood of concussion

Stress Measurement in Primary Care: Conceptual Issues, Barriers, Resources, and Recommendations for Study

Objective: Exposure to stressors in daily life and dysregulated stress responses are associated with increased risk for a variety of chronic mental and physical health problems, including anxiety disorders, depression, asthma, heart disease, certain cancers, and autoimmune and neurodegenerative disorders. Despite this fact, stress exposure and responses are rarely assessed in the primary care setting and infrequently targeted for disease prevention or treatment. Method: In this narrative review, we describe the primary reasons for this striking disjoint between the centrality of stress for promoting disease and how rarely it is assessed by summarizing the main conceptual, measurement, practical, and reimbursement issues that have made stress difficult to routinely measure in primary care. The following issues will be reviewed: (1) assessment of stress in primary care; (2) biobehavioral pathways linking stress and illness; (3) the value of stress measurements for improving outcomes in primary care; (4) barriers to measuring and managing stress; and (5) key research questions relevant to stress assessment and intervention in primary care. Results: Based on our synthesis, we suggest several approaches that can be pursued to advance this work, including feasibility and acceptability studies, cost-benefit studies, and clinical improvement studies. Conclusions: Although stress is recognized as a key contributor to chronic disease risk and mortality, additional research is needed to determine how and when instruments for assessing life stress might be useful in the primary care setting, and how stress-related data could be integrated into disease prevention and treatment strategies to reduce chronic disease burden and improve human health and wellbeing