SQUEAK AND RATTLE PREVENTION BY GEOMETRIC VARIATION MANAGEMENT USING A TWO-STAGE EVOLUTIONARY OPTIMISATION APPROACH

Squeak and rattle are annoying sounds that are often regarded as the failure indicators by car users. Geometric variation is a key contributor to the generation of squeak and rattle sounds. Optimisation of the connection configuration in assemblies can be a provision to minimise this risk. However, the optimisation process for large assemblies can be computationally expensive. The focus of this work is to propose a two-stage evolutionary optimisation scheme to find the fittest connection configurations that minimise the risk for squeak and rattle. This was done by defining the objective functions as the measured variation and deviation in the rattle direction and the squeak plane. In the first stage, the location of the fasteners primarily contributing to the rattle direction measures are identified. In the second stage, fasteners primarily contributing to the squeak plane measures are added to the fittest configuration from phase one. It was assumed that the fasteners from the squeak group plane have a lower-order effect on the rattle direction measures, compared to the fasteners from the rattle direction group. This assumption was falsified for a set of simplified geometries. Also, a new uniform space filler algorithm was introduced to efficiently generate an inclusive and feasible starting population for the optimisation process by incorporating the problem constraints in the algorithm. For two industrial cases, it was shown that by using the proposed two-stage optimisation scheme the variation and deviation measures in critical interfaces for squeak and rattle improved compared to the baseline results.

Tissue mimetic hyaluronan bioink containing collagen fibers with controlled orientation modulating cell morphology and alignment

Biofabrication is providing scientists and clinicians the ability to produce engineered tissues with desired shapes, and gradients of composition and biological cues. Typical resolutions achieved with extrusion-based bioprinting are at the macroscopic level. However, for capturing the fibrillar nature of the extracellular matrix (ECM), it is necessary to arrange ECM components at smaller scales, down to the micron and the molecular level.In this study, we introduce a bioink containing hyaluronan (HA) as tyramine derivative (THA) and collagen type 1 (Col 1). Similarly to other connective tissues, in this bioink Col is present in fibrillar form and HA as viscoelastic space filler. THA was enzymatically crosslinked under mild conditions allowing simultaneous Col fibrillogenesis, thus achieving a homogeneous distribution of Col fibrils within the viscoelastic HA-based matrix. THA-Col composite displayed synergistic properties in terms of storage modulus and shear-thinning, translating into good printability.Shear-induced alignment of the Col fibrils along the printing direction was achieved and quantified via immunofluorescence and second harmonic generation. Cell-free and cell-laden constructs were printed and characterized, analyzing the influence of the controlled microscopic anisotropy on human bone marrow derived mesenchymal stromal cells (hMSC) migration.THA-Col showed cell instructive properties modulating hMSC adhesion, morphology and sprouting from spheroids stimulated by the presence and the orientation of Col fibers. Actin filament staining showed that hMSCs embedded into aligned constructs displayed increased cytoskeleton alignment along the fibril direction. Based on gene expression of cartilage/bone markers and ECM production, hMSCs embedded into the bioink displayed chondrogenic differentiation comparable to standard pellet culture by means of proteoglycan production (Safranin O staining and proteoglycan quantification).The possibility of printing matrix components with control over microscopic alignment brings biofabrication one step closer to capturing the complexity of native tissues.

Hard Tissue Augmentation of Aged Bone by Means of a Tin-Free PLLA-PCL Co-Polymer Exhibiting in vivo Anergy and Long-Term Structural Stability

Background: Due to aging, tissue regeneration gradually declines. Contemporary strategies to promote tissue-specific regeneration, in particular in elderly patients, often include synthetic material apt for implantation primarily aiming at upholding body functions and regaining appropriate anatomical and functional integrity. Objective: Biomaterials suitable for complex reconstruction surgical procedures have to exert high physicochemical stability and biocompatibility. Method: A polymer made of poly-L-lactic acid and poly-ε-caprolactone was synthesized by means of a novel tin-free catalytic process. The material was tested in a bioreactor-assisted perfusion culture and implanted in a sheep model for lateral augmentation of the mandible. Histological and volumetric evaluation was performed 3 and 6 months post-implantation. Results: After synthesis the material could be further refined by cryogrinding and sintering, thus yielding differently porous scaffolds that exhibited a firm and stable appearance. In perfusion culture, no disintegration was observed for extended periods of up to 7 weeks, while mesenchymal stromal cells readily attached to the material, steadily proliferated, and deposited extracellular calcium. The material was tested in vivo together with autologous bone marrow-derived stromal cells. Up to 6 months post-implantation, the material hardly changed in shape with composition also refraining from foreign body reactions. Conclusion: Given the long-term shape stability in vivo, featuring imperceptible degradation and little scarring as well as exerting good compatibility to cells and surrounding tissues, this novel biomaterial is suitable as a space filler in large anatomical defects.

Perencanaan Lanskap Ekowisata Hutan Mangrove Di Pantai Sari Ringgung Desa Sidodadi Kecamatan Padang Cermin Kabupaten Pesawaran

Ecotourism is a utilization of mangrove forest ecosystems in a sustainable manner through tourism activities that are responsible to environment. The application of the ecotourism concept in the mangrove forest area in Sari Ringgung Beach Sidodadi Village of Padang Cermin Pesawaran is expected to reduce the damage to mangrove ecosystems by increasing public awareness of the mangroves existence. This research objectives are to develop a plan of mangrove forest ecotourism through the exploration landscape potential in the form of biophysical elements and social community. Ecotourism planning activities consist of an potential inventory, analysis, synthesis, scheming concepts, and tread design. Inventory data results are categorized into the potential and constraints are analyzed logically to obtain the synthesis results. Space zoning development plan was produced at the planning stage as the basic design of the space concept, circulation paths, and green governance. Mangrove forest in Sari Ringgung Beach has ecotourism potential including physical and visual condition, plants diversity and mangrove wildlife animals, visitors crowd, and good community support. Ecotourism plan is designed by the spatial distribution of ecotourism into 15 ha as reception area, 2 ha as service area, 68 ha as buffer area, and 12 ha as ecotourism area. Ecotourism access is developed in three path circulation are: paving block path in the dry land route, boardwalk path to cross the wetlands, and ships route to cross the open beach. Coconut and Pine selected as a space filler plants and various types of mangrove as wetlands rehabilitation plants. Kata kunci: ecotourism, mangrove, landscape planning