Ionospheric electron content at temperate latitudes during the declining phase of the sunspot cycle

Ionospheric electron density during declining phase of sunspot cycle by Faraday effect observation

Wave propagation and earth satellite radio emission studies

Radio propagation studies of the ionosphere using satellite radio beacons are described. The ionosphere is known as a dispersive, inhomogeneous, irregular and sometimes even nonlinear medium. After traversing through the ionosphere the radio signal bears signatures of these characteristics. A study of these signatures will be helpful in two areas: (1) It will assist in learning the behavior of the medium, in this case the ionosphere. (2) It will provide information of the kind of signal characteristics and statistics to be expected for communication and navigational satellite systems that use the similar geometry

Feasibility of Thermoplastic Extrusion Welding as a Joining Method For Vacuum-Assisted Additively Manufactured Tooling

In recent years, additive manufacturing (AM) has been successfully utilized for the production of large-scale composite tooling. Within these endeavors, however, limited research has focused on joining methods between printed sections. This work evaluates the feasibility of thermoplastic extrusion welding as a joining method for additively manufactured tooling structures. This joining method was assessed based on industry specifications of conventional thermoset tooling for wind blade manufacturing utilizing the vacuum-assisted resin transfer molding (VARTM) process. The specifications include requirements for the mechanical strength, vacuum integrity, roughness, and hardness of the tool surface. The feasibility of this welded polymer joint was demonstrated through subscale testing of 1” thick, welded, AM high-impact polystyrene (HIPS) plates. It was found that thermoplastic extrusion welds within AM components can maintain vacuum integrity at 20℃ with proper surface preparation and without a surface coating. This met the industry vacuum leakage specification of 10 millibar over 30 minutes with an average loss of 6.61 mbar over 30 minutes through the welded AM plate and bag system. Although beyond the industry specification, the vacuum leakage was further tested to evaluate performance at an infusion temperature of 80℃. At elevated temperature, the joint and plate lost approximately 26 mbar over 30 minutes. The surface finish was compared with hardness and roughness testing of the welded and machined AM surfaces, showing a decrease in hardness and roughness in the surface of the weld at both temperatures. Standardized ASTM mechanical testing of welded specimens showed an average comparative tensile strength of 80% of the base AM HIPS material. With the addition of undersurface reinforcement within the mold and a surface coating, extrusion welding shows promise for joining large-scale AM tool sections in a manufacturing environment

Alien Registration- Pooler, Frances C. (Madison, Somerset County)

https://digitalmaine.com/alien_docs/7028/thumbnail.jp

Micro-Computed Tomography Analysis of Subchondral Bone Regeneration Using Osteochondral Scaffolds in an Ovine Condyle Model

Osteochondral scaffold technology has emerged as a promising therapy for repairing osteochondral defects. Recent research suggests that seeding osteochondral scaffolds with bone marrow concentrate (BMC) may enhance tissue regeneration. To examine this hypothesis, this study examined subchondral bone regeneration in scaffolds with and without BMC. Ovine stifle condyle models were used for the in vivo study. Two scaffold systems (8 mm diameter and 10 mm thick) with and without BMC were implanted into the femoral condyle, and the tissues were retrieved after six months. The retrieved femoral condyles (with scaffold in) were examined using micro-computed tomography scans (micro-CT), and the micro-CT data were further analysed by ImageJ with respect to trabecular thickness, bone volume to total volume ratio (BV/TV) ratio, and degree of anisotropy of bone. Statistical analysis compared bone regeneration between scaffold groups and sub-set regions. These results were mostly insignificant (p < 0.05), with the exception of bone volume to total volume ratio when comparing scaffold composition and sub-set region. Additional trends in the data were observed. These results suggest that the scaffold composition and addition of BMC did not significantly affect bone regeneration in osteochondral defects after six months. However, this research provides data which may guide the development of future treatments

Bedded Pack Management System Case Study

Agribusiness, Agricultural Finance, Farm Management,

Adolescents’ perceptions of long-term effects of cycle skilltraining

Cycling to school is uncommon among adolescents in most developed countries. Development of cycling skills through cycle skills training (CST) can reduce cycling-related safety concerns. This study examined long-term effects of CST retrospectively by comparing adolescents’ perceptions of cycling to school and their confidence to cycle to school among those who participated in CST in primary and/or intermediate school with non-participants. Adolescents (n=1,260; 51% female; 12 schools) from Dunedin (New Zealand) completed an online survey at school. Adolescents self-reported transport modes to school, perceptions of cycling to school and CST, and previous participation in and perceived benefits of school-based CST programmes. Only 1-2% adolescents usually cycled to school. Overall, 42% agreed CST would make them safer in traffic (no significant difference between CST participants (n=512) and non-participants (n=748)). Among CST participants, 32% reported that CST increased their confidence to cycle to school and those adolescents had more favourable attitudes towards CST than participants who reported no effects. In a multivariable analysis, adolescents’ perceptions that CST increased their cycling confidence were positively associated with self-efficacy for cycling to school (odds ratio (OR) (95% confidence interval (CI)): 1.33 (1.07, 1.67)), perceived school support (1.51 (1.01, 2.25)), parental cycling-related safety concerns (1.84 (1.25, 2.69)) and being Māori (6.47 (2.36, 17.7)) or other ethnic origins (2.26 (1.00, 5.10); reference: New Zealand Europeans). Therefore, CST could be a useful strategy to support adolescents’ cycling to school, ideally (as suggested in the literature) in combination with appropriate infrastructure changes and speed management measures