Hydrofoils with Differing Leading-Edge Protuberances: CFD and Experimental Investigations

Leading-edge protuberances on the pectoral fin of humpback whales have been widely adopted to the designs of foils to provide superior lifting characteristics in the post-stall regimes. The present work investigates the lift, drag and flow characteristics of finite-span rectangular hydrofoils having different configurations of two protuberances over the leading edge with NACA 634-021 as the base design section. The results obtained from CFD analyses are validated using lift and drag measurements from experiments. The influence of using a transition-sensitive turbulence model on the results is investigated. It is observed that, in general, a foil with smaller separation between protuberances has better post-stall lift characteristics whereas that with protuberances at larger separation have better pre-stall characteristics. Depending on the separation between them, streamwise vortices are generated from the leading-edge protuberances. The two protuberances can restrict the zone of separation between them at high angles of attack. The influence of Reynolds number on the lifting performance is also investigated.

Additive Manufacturing of a Shredder

Shredders have become an indispensable pail of modern life. Variety of shredders are available for different purposes such as Paper shredders, metal shredders, etc. They come in different sizes, ranging from small sizes for household applications to large sizes for industrial applications. These shredders are used to break down the material into smaller pieces so that they could be disposed of more easily and efficiently. Currently, these shredders are majorly used by large industries for waste disposal systems. This process of shredding the large waste produced by common households by itself will take an enormous amount of energy when accumulated overall as they mainly use fossil fuels for this purpose. This can be reduced by reducing to an extent if all the possible household waste is manually shredded at houses themselves instead of taking it to the industries. For this purpose. in this study, an economical shredder that has the capability to plastics, wood, and few low strength metals like aluminium has been designed. Beginning with a base design and have worked to improvise it in considered parameters. These parameters are the shredder being efficient, economical, and lighter. The design was repaired and optimized in Meshmixer Software and then sliced in Ultimaker Cura Software and was made 3-D printable. The developed model was found to be more helpful than the conventional shredders, as to its economical viability, ease in use and handling, and to its efficiency in shredding the plastics. As a result, a successful and efficient design of a portable shredder has been developed.

PEGASOS - A New Linking Mechanism for Modular Osteosynthesis Plates in Minimally Invasive Acetabular Surgery

Background: Recently presented minimally invasive endoscopic surgical techniques demonstrated the feasibility of implanting standard osteosynthesis plates for pelvic fractures. The reconstruction and internal fixation of complex acetabular fractures is still challenging. The goal of this study is to introduce a divisible implant, with a positive-locking in situ linking mechanism for plate osteosynthesis, making it possible to stabilize large and complex acetabular fractures with involvement of the quadrilateral surface. Method: Standard implants were used to recreate a base design. Using computer aided design (CAD), a three-dimensional standard implant was divided into two parts, so they could be re-allocated in situ. A critical objective was to reduce the cross-section of each part (clearance gauge). To connect the separated parts in situ, a new linking mechanism (cone in cone) was created. The new construct also features self-stabilization, self-centering, reinforced positional movement and preloading effects. Results: A linking system for plate osteosynthesis was developed entitled PEGASOS ("Percutaneous Endoscopic Guided Acetabulum-Stabilizing Osteosynthesis System"). Endoscopic implantation and in-situ-linking could be performed in a human cadaver. Therefore, we could demonstrate, that buttressing the quadrilateral surface of the acetabulum could be performed minimally invasive using a divisible suprapectineal buttress plate. Conclusion: We created a linking mechanism to couple two plates in situ. This mechanism enables an extremely strong, positive-locking connection, whereas its geometric shape allows for different relative movements during the locking procedure, with a single screw.

Transient thermal analyses of an integrated brake rotor and wheel hub for heavy duty vehicles

In this study, transient thermal analyses for a new integrated rotor and wheel hub concept are performed by consideration of convection, conduction and radiation effects. Test methods used for the characterization and certification purposes are constructed in a simulation environment and the effect of different ventilation vanes and rotor-hub arrangements on heat transfer mechanism is examined and the details are summarized for a reliable simulation process. Validated procedures are used to report a series of characterization and certification analyses, namely; CFD analyses including wheel assembly, cooldown analyses, R13 repeated stop fade and alpine hot descent analyses for current design and new integrated rotor and hub pair for alternative ventilation vane designs. The analyses are especially focused on predicting the cooling period and predicting maximum bearing temperatures for normal and excessive loading scenarios. To provide benchmark a commercial integrated rotor and hub pair used in heavy duty vehicles is also analysed. The average convective heat transfer coefficient and cooldown period of proposed integrated brake rotor are improved by 117.3% and 30.5% compared to the base design. The maximum wheel bearing temperature is decreased by 27.0% and by 27.1% for the proposed integrated brake rotor and wheel hub compared to the benchmark model, in accordance with the repeated stop and alpine hot descent analyses. In addition, the total weight reduction of 10 kg (15%) according to the base design is achieved.

USING INQUIRY-BASED LEARNING TO EXPLORE RESPECT OF CULTURAL BASE DESIGN: A CASE STUDY IN AMPHAWA TOURISM COMMUNITY, THAILAND

Amphawa is a Thai valuable cultural heritage. This cultural tourism has been amplified thanks to the UNESCO award. Despite the recognition, there exists a conflict as seen obviously in the town development by cross-cultural designers. This research focuses on establishment of a proper learning model. Qualitative research was undertaken using a tool namely Ethnographic Delphi Futures Research. The results found that the method of Inquiry-Based Learning significantly made learners gain insights because of the direct interactions with the community stakeholders who truly take part in reaching the consensus which improved consistency of the design works to preserve the cultural identity.

Carry-Propagation-Adder-Factored Gemmini Systolic Array for Machine Learning Acceleration

Systolic arrays are the primary part of modern deep learning accelerators and are being used widely in real-life applications such as self-driving cars. This paper presents a novel factored systolic array, where the carry propagation adder for accumulation and the rounding logic are extracted out from each processing element, which reduces the area, power and delay of the processing elements substantially. The factoring is performed in the column-wise manner and the cost of the factored logic, placed at each column output, is amortized by the processing elements in a column. We demonstrate the proposed factoring in an open source systolic array, Gemmini. The factoring technique does not change the functionality of the base design and is transparent to applications. We show that the proposed technique leads to substantial reduction in area and delay up to 45.3% and 23.7%, respectively, compared to the Gemmini baseline.