Study Of Wave-Induced Scour Depth Around Group Of Piles Using Support Vector Machines

Various arrangements of pile groups are widely being used as supports of marine structures. As piles are located on erodible beds of the sea, scouring is a threat to such structures and the scour depth amounts should be considered well in their designs. Though most of these supports are constructed in form of groups of piles, majority of studies were concentrated on predictions of scouring around single piles whereas the arrangement of the piles and the spaces between them in arrangements as well as their geometry, sediment and wave characteristics should also be studied. Despite the importance of the scour hole depths, the existing prediction formulas are not capable of accurate estimations around pile groups with different arrangements. Hence, developing a robust model for the estimation of scour depth seems necessary. One of the most common approaches as an alternative to empirical ones is the soft computing methods. Artificial Neural Network as the most famous data-mining method has been successfully applied in scour studies. But there are still needs of more assessments in their applications on pile group case studies. In addition, Support Vector Machines as one of the recently applied soft computing models in scouring has scarcely been studied so far. In this study, series of large scale scouring experiments were done for various arrangements of pile groups with different pile and arrangement characteristics exposed to waves of shallow water and equilibrium scour depth around them were measured in wave basin of Ujigwa Open Laboratory of Kyoto University. Finally, by applying the provided experimental data, the applicability of data mining models were assessed in predictions of pile group scour properties. Results indicate that, data mining approaches can provide more reliable predictions of scouring properties due to waves compared to current available empirical formulae

Bioactive Wound Dressing Gauze Loaded with Silver Nanoparticles Mediated by Acacia Gum

A wound dressing is very crucial component in wound healing process. Bioactive dressings play important role in wound sterilization and promote tissue healing and growth. The present work investigated the preparation of AgNPs in solid-state using acacia gum as both reductant and stabilizing agent. Sodium hydroxide (NaOH) was employed as activating agent and pH mediator. Acacia is a naturally occurring mixture of polysaccharides and glycoproteins. The obtained particles were in the range of 50 nm. The work was extended to evaluate the antimicrobial of AgNPs treated gauze cotton fabrics against gram positive (S. aureus), gram negative (P. aeruginosa) bacteria,C. albicans(yeast); andA. Niger(fungus). The inhibition zone of the as prepared silver nanoparticles was found to be 24 mm against both types of bacteria, 23 mm againstC. albicans(yeast), and inactive againstA. Niger(fungus). On the other hand, the treated gauze showed bactericidal behavior and a clear zone was found underneath the samples on the agar plate. The reduction percent in number of bacterial colonies of treated gauze fabrics in comparison to controlPseudomonas aeruginosaculture showed a reduction up to 100%. The aforementioned results promote the acquirement of bioactive antibacterial wound dressing

Mechanical characterization of a novel biomimetic artificial disc for the cervical spine

A novel biomimetic artificial intervertebral disc (bioAID) replacement implant has been developed containing a swelling hydrogel representing the nucleus pulposus, a tensile strong fiber jacket as annulus fibrosus and titanium endplates with pins to primarily secure the device between the vertebral bodies. In this study, the design safety of this novel implant was evaluated based on several biomechanical parameters, namely compressive strength, shear-compressive strength, risk of subsidence and device expulsion as well as identifying the diurnal creep-recovery characteristics of the device. The bioAID remained intact up to 1 kN under static axial compression and only 0.4 mm of translation was observed under a compressive shear load of 20 N. No subsidence was observed after 0.5 million cycles of sinusoidal compressive loading between 50 and 225 N. After applying 400 N in antero-posterior direction under 100 N axial compressive preload, approximately 2 mm displacement was found, being within the range of displacements reported for other commercially available cervical disc replacement devices. The diurnal creep recovery behavior of the bioAID closely resembled what has been reported for natural intervertebral discs in literature. Overall, these results indicate that the current design can withstand (shear-compression loads and is able to remain fixed in a mechanical design resembling the vertebral bodies. Moreover, it is one of the first implants that can closely mimic the poroelastic and viscoelastic behavior of natural disc under a diurnal loading pattern

Biomechanical evaluation of a novel biomimetic artificial intervertebral disc in canine cervical cadaveric spines

Background Context Cervical disc replacement (CDR) aims to restore motion of the treated level to reduce the risk of adjacent segment disease (ASD) compared with spinal fusion. However, first-generation articulating devices are unable to mimic the complex deformation kinematics of a natural disc. Thus, a biomimetic artificial intervertebral CDR (bioAID), containing a hydroxyethylmethacrylate (HEMA)—sodium methacrylate (NaMA) hydrogel core representing the nucleus pulposus, an ultra-high-molecular-weight-polyethylene fiber jacket as annulus fibrosus, and titanium endplates with pins for primary mechanical fixation, was developed. Purpose To assess the initial biomechanical effect of the bioAID on the kinematic behavior of the canine spine, an ex vivo biomechanical study in 6-degrees-of-freedom was performed. Study Design A canine cadaveric biomechanical study. Methods Six cadaveric canine specimens (C3-C6) were tested in flexion-extension (FE), lateral bending (LB) axial rotation (AR) using a spine tester in three conditions: intact, after C4-C5 disc replacement with bioAID, and after C4-C5 interbody fusion. A hybrid protocol was used where first the intact spines were subjected to a pure moment of ±1 Nm, whereafter the treated spines were subjected to the full range of motion (ROM) of the intact condition. 3D segmental motions at all levels were measured while recording the reaction torsion. Biomechanical parameters studied included ROM, neutral zone (NZ), and intradiscal pressure (IDP) at the adjacent cranial level (C3-C4). Results The bioAID retained the sigmoid shape of the moment-rotation curves with a NZ similar to the intact condition in LB and FE. Additionally, the normalized ROMs at the bioAID-treated level were statistically equivalent to intact during FE and AR while slightly decreased in LB. At the two adjacent levels, ROMs showed similar values for the intact compared to the bioAID for FE and AR and an increase in LB. In contrast, levels adjacent to the fused segment showed an increased motion in FE and LB as compensation for the loss of motion at the treated level. The IDP at the adjacent C3-C4 level after implantation of bioAID was close to intact values. After fusion, increased IDP was found compared with intact but did not reach statistical significance. Conclusion This study indicates that the bioAID can mimic the kinematic behavior of the replaced intervertebral disc and preserves that for the adjacent levels better than fusion. As a result, CDR using the novel bioAID is a promising alternative treatment for replacing severely degenerated intervertebral discs

円柱杭群まわりにおける波による洗掘現象に関する研究

京都大学0048新制・課程博士博士(工学)甲第18558号工博第3919号新制||工||1602(附属図書館)31458京都大学大学院工学研究科社会基盤工学専攻(主査)教授 平石 哲也, 教授 間瀬 肇, 准教授 馬場 康之学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDFA