Large Strain Extrusion Machining of AA7050

Aluminum has remained among the most commonly-used materials for aerospace applications for the past 100 years. It is advantageous due to its relatively high strength, low weight, ease of forming, electrical and thermal conductivity, and low cost. Alloy 7050 is among highest strength aerospace-grade aluminum alloys and can be formed into a wide variety of shapes via extrusion, rolling, forging, and other processes. Unfortunately, consistent and homogenous process control can be difficult to achieve during these bulk forming operations due to the complexity of the Al-Zn-Mg-Cu alloy system. Poor process control can result in defects and/or inhomogeneous microstructures and properties, during either deformation or during post-deformation heat treatment. It is therefore desirable to learn more about the nature and mechanisms of microstructural evolution during bulk deformation processes, and it may also be desirable to seek alternative production methods where possible. Large strain extrusion machining (LSEM) is a simultaneous cutting-extrusion process that has been applied to AA7050 in this work. It is a single-step deformation process that is used both as a tool to explore deformation in general, and also as a potential alternative method to produce AA7050-T7 plate, one of the most commonly used forms of the material. Experiments in this work include LSEM starting from different initial microstructural conditions and different deformation conditions. Specifically, hardened AA7050-T7451 material, which is typically impossible to process due to its high strength and low workability, has been processed via LSEM at an effective strain larger than 1 to create continuous AA7050 plate with very smooth surfaces in a single deformation step. Room temperature LSEM has also been applied in this work to produce plate from Otempered, as-cast, and as-homogenized AA7050. Results from experiments with these softer materials show the limitations of the LSEM process. Sticking friction, especially at slow cutting speeds, causes problems that lead to built-up edges at the strip-tool interfaces and poor surface quality. While continuous strips with good surface quality is possible for both annealed and ashomogenized material, careful balance must be maintained between cutting quickly enough to limit sticking friction but slowly enough to limit strain rate and adiabatic heating. After proper balance and control of these considerations was achieved, LSEM plate created from ashomogenized material was artificially aged successfully to create a product with properties similar to conventionally-rolled AA7050-T7451 plate

Weather, Timing, and Promotions in Minor League Baseball: An Examination of Attendance in the International League

Understanding the different factors that impact attendance at sporting events is a timely and relevant topic for researchers and practitioners alike. The present study examines the effects of different types of promotions, weather, and selected temporal elements on attendance in Minor League Baseball. Using data for teams participating in the International League during the 2010 season, results from a multiple regression analysis revealed that special events, promotional giveaways, and non-workdays have a positive impact on attendance; while suboptimal weather conditions have a negative impact. These findings contribute to our understanding of the factors that impact attendance in professional baseball and hold useful implications for future research and managerial practice

Trails and Physical Activity: A Review

To provide a synthesis of research on trails and physical activity from the public health, leisure sciences, urban planning, and transportation literatures. Methods: A search of databases was conducted to identify studies published between 1980 and 2008. Results: 52 studies were identified. The majority were cross-sectional (92*%) and published after 1999 (11%). The evidence for the effects of trails on physical activity was mixed among 3 intervention and 5 correlational studies. Correlates of trail use were examined in 13 studies. Several demographic (eg, race, education, income) and environmental factors (eg, land-use mix and distance to trail) were related to trail use. Evidence from 31 descriptive studies identified several facilitators and barriers to trail use. Economic studies (n = 5) examining trails in terms of health or recreational outcomes found trails are cost-effective and produce significant economic benefits. Conclusion: There is a growing btidy of evidence demonstrating important factors that should be considered in promoting trail use, yet the evidence for positive effects of trails on physical activity is limited. Further research is needed to evaluate the effects of trails on physical activity. In addition, trail studies that include children and youth, older adults, and racial and ethnic minorities are a research priority

Compressive and Bending Performance of Selectively Laser Melted AlSi10Mg Structures

Selective laser melting (SLM) is a widely used additive manufacturing technique that effectively manufactures complex geometries such as cellular structures. However, challenges such as anisotropy and mechanical property variation are commonly found due to process parameters. In a bid to utilize this method for the commercial production of cellular structures, it is important to understand the behavior of a material under different loading conditions. In this work, the behavior of additively manufactured AlSi10Mg under compression, bending, and tension loads was investigated. Vertical and horizontal build directions are compared for each type of loading. Specimens were manufactured using the reduced build volume (RBV) chamber of the Renishaw AM 250 SLM machine

Accelerometer and GPS Data to Analyze Built Environments and Physical Activity

Purpose: Most built environment studies have quantified characteristics of the areas around participants' homes. However, the environmental exposures for physical activity (PA) are spatially dynamic rather than static. Thus, merged accelerometer and global positioning system (GPS) data were utilized to estimate associations between the built environment and PA among adults. Methods: Participants (N = 142) were recruited on trails in Massachusetts and wore an accelerometer and GPS unit for 1-4 days. Two binary outcomes were created: moderate-to-vigorous PA (MVPA vs. light PA-to-sedentary); and light-to-vigorous PA (LVPA vs. sedentary). Five built environment variables were created within 50-meter buffers around GPS points: population density, street density, land use mix (LUM), greenness, and walkability index. Generalized linear mixed models were fit to examine associations between environmental variables and both outcomes, adjusting for demographic covariates. Results: Overall, in the fully adjusted models, greenness was positively associated with MVPA and LVPA (odds ratios [ORs] = 1.15, 95% confidence interval [CI] = 1.03, 1.30 and 1.25, 95% CI = 1.12, 1.41, respectively). In contrast, street density and LUM were negatively associated with MVPA (ORs = 0.69, 95% CI = 0.67, 0.71 and 0.87, 95% CI = 0.78, 0.97, respectively) and LVPA (ORs = 0.79, 95% CI = 0.77, 0.81 and 0.81, 95% CI = 0.74, 0.90, respectively). Negative associations of population density and walkability with both outcomes reached statistical significance, yet the effect sizes were small. Conclusions: Concurrent monitoring of activity with accelerometers and GPS units allowed us to investigate relationships between objectively measured built environment around GPS points and minute-by-minute PA. Negative relationships between street density and LUM and PA contrast evidence from most built environment studies in adults. However, direct comparisons should be made with caution since most previous studies have focused on spatially fixed buffers around home locations, rather than the precise locations where PA occurs

Performance Evaluation Of Composite Sandwich Structures With Additively Manufactured Aluminum Honeycomb Cores With Increased Bonding Surface Area

Modern aerostructures, including wings and fuselages, increasingly feature sandwich structures due to their high-energy absorption, low weight, and high flexural stiffness. The face sheet of these sandwich structures are typically thin composite laminates with interior honeycombs made of Nomex or aluminum. Standard cores are structurally efficient, but their design cannot be varied throughout the structure. With additive manufacturing (AM) technology, these core geometries can be altered to meet the design requirements that are not met in standard honeycomb cores. This study used a modified aluminum honeycomb core, with increased surface area on the top and bottom, as the core material in sandwich panels. The modified honeycomb core was produced through the laser powder bed fusion method. The behavior of the modified sandwich composite panels was evaluated through three-point bend, edgewise compression, and impact tests, and their performance was compared to that of a conventional honeycomb core sandwich panel. The three-point bend test results indicated that the sandwich structure\u27s ultimate shear strength improved by 12.6% with the modified honeycomb core. Additionally, the displacement at the failure of the structure increased by 11%. The edgewise compression tests showed that the ultimate edgewise compressive strength improved by 19.1% when using the modified core. The impact test results revealed that the peak force increased by 8% and the energy-absorbing capacity of the sandwich structure increased by 20% with the use of the modified honeycomb core

Adding Psychological Value to Heritage Tourism Experiences

This study employed an under-utilized methodology known as the Hierarchical Value Map (HVM) technique to explore the underlying motives and needs of visitors to a heritage site. Drawing from a small sample of visitors to a preserved 18th century plantation, the analysis revealed that most respondents were looking for a satisfying leisure experience where pleasure and learning are complementary. In addition the results support the notion that there is a specialized tourist segment (e.g., heritage tourists) that as a group has unique motives and needs. Implications for both optimizing the visitors experience as well as projecting an effective image and marketing communications are discussed

Consuming post-disaster destinations: The case of Sichuan, China

Addressing the call for a better understanding of tourist behavior in relation to post-disaster destinations, this study explores the motivations and intentions of potential domestic tourists (from non-hit areas) to visit Sichuan, China in the aftermath of an earthquake. Drawing on dark tourism theories, this study offers a more comprehensive insight into the consumption of post-disaster destinations, aiming to capture the impact of the changes to the destination’s attributes on tourist behavior. The findings move beyond the common approach to tourism recovery, which solely focuses on reviving the traditional ‘‘non-dark’’ products. This study reveals the importance of newly formed dark attributes that emerge from the disaster as another means to destination recovery, reflected in the emergence of new tourist segments

Why Wine Tourists Visit Cellar Doors: Segmenting Motivation and Destination Image.

This study examines the relationship between the motivation of wine tourists to visit cellar doors and destination image perception. A survey of tourists resulted in 676 useable questionnaires. Using a novel segmentation method, self organizing maps (SOM) and bagged clustering (BC), the study identified five distinct motivation clusters. These clusters were different on only gender and previous visit to the wine region. Three clusters of destination image were identified using the same segmentation method. Significant relationships were found between the motivation and destination image clusters. Implications for destination marketing and managing the tourist experience at the winery cellar door are discussed

Bagged fuzzy clustering for fuzzy data: An application to a tourism market.

Segmentation has several strategic and tactical implications in marketing products and services. Despite hard clustering methods having several weaknesses, they remain widely applied in marketing studies. Alternative segmentation methods such as fuzzy methods are rarely used to understand consumer behaviour. In this study, we propose a strategy of analysis, by combining the Bagged Clustering (BC) method and the fuzzy C-means clustering method for fuzzy data (FCM-FD), i.e., the Bagged fuzzy C-means clustering method for fuzzy data (BFCM-FD). The method inherits the advantages of stability and reproducibility from BC and the flexibility from FCM-FD. The method is applied on a sample of 328 Chinese consumers revealing the existence of four segments (Admirers, Enthusiasts, Moderates, and Apathetics) of the perceived images of Western Europe as a tourist destination. The results highlight the heterogeneity in Chinese consumers' place preferences and implications for place marketing are offered