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In order to reduce the damage to tissue and fill the interstices between fibers, multifilament sutures are frequently treated with certain coating materials. The objective of this study was to create and characterize dopamine hydrochloride (DA) and carboxymethyl chitosan (CMCS) coatings on surgical sutures and investigate their effects on the frictional performance of the surgical sutures during sliding through a skin substitute. The effects of the treatment on the physical and chemical characteristics of the surgical sutures were evaluated. The friction force of the surgical sutures during sliding through the skin substitute was experimentally determined using a penetration friction apparatus. The coefficient of friction (COF) was calculated using a linear elastic model and was used to estimate the frictional behavior of the surgical suture-skin interactions. The results showed that the DA coating could evenly deposit on the surface of the etched multifilament surgical suture surfaces in a weakly alkaline buffer solution. The CMCS coating material could form a uniform film on the surface of the sutures. Minor changes in the surface roughness of the multifilament surgical sutures with different treatments occurred in this study. The friction force and the COF of the multifilament surgical sutures with DA and CMCS coating showed little change when compared with untreated multifilament surgical sutures., Railway Engineering

Surface texture is important for contact mechanical and tribological phenomena such as the contact area and friction. In this research, three different types of geometrical microstructures were designed and fabricated by pulsed laser surface texturing as semi-symmetric (grooved channel), asymmetric fractal (Hilbert curve), and symmetric patterns (grid). A conventionally finished surface as a reference sample from the same stainless steel sheet material was compared. From the experimental approach, a multiaxis force/torque transducer was used to investigate the functionality of surface texture based on measuring the tactile friction in three different sliding directions: perpendicular, parallel, and 45° to the textures. According to the dynamic friction measurements, the grid texture was indeed orientation independent. The other samples showed orientation-dependent frictional behavior, especially the grooved channel texture and reference sample. Furthermore, an analytical approach was applied to estimate the values of the friction coefficient by the pressure distribution method. From both the experimental and analytical approaches, the grid pattern was validated to be the optimal texture design in the concern of friction reduction and orientation-independent behavior., Railway Engineering

Tactile perception is a complex system, which depends on frictional interactions between skin and counter-body. The contact mechanics of tactile friction is governed by many factors such as the state and properties of skin and counter-body. In order to discover the connection between perception and tactile friction on textured stainless steel sheets, both perception experiments (subjective) and tactile friction measurements (objective) were performed in this research. The perception experiments were carried out by using a panel test method to identify the perceived roughness, perceived stickiness and comfort level from the participants. For the friction experiments, tactile friction was measured by a multi-axis force/torque transducer in vivo. The perceived stickiness was illustrated as an effective subjective stimulus, which has a negative correlation to the comfort perception. No significant evidence was revealed to the connection between the perceived roughness and comfort perception, and this relationship may be influenced by the participants’ individual experience, gender and moisture level of skin. Furthermore, the kinetic tactile friction was concluded as an objective stimulus to the comfort perception with a negative correlation., Railway Engineering

Tribological interactions between surgical suture and human tissue play an important role in the stitching process. The purpose of the paper is to understanding the tribological behavior of surgical suture interacting with artificial skin, with respect to surgical suture material and structure, by means of a capstan experiment approach and a contact area model. The results indicated that structure and surface topography of the surgical suture had a pronounced effect on the tribological interactions. The apparent coefficient of friction of vicryl surgical suture was the smallest among the three surgical suture materials. As the sliding velocity increased, or the applied load decreased, the coefficient of friction increased. Furthermore, stick-slip phenomena were observed during the sliding procedure., Railway Engineering

This review gives a concise introduction to the state-of-art techniques used for surface texturing, e.g., wet etching, plasma etching, laser surface texturing (LST), 3D printing, etc. In order to fabricate deterministic textures with the desired geometric structures and scales, the innovative texturing technologies are developed and extended. Such texturing technology is an emerging frontier with revolutionary impact in industrial and scientific fields. With the help of the latest fabrication technologies, surface textures are scaling down and more complex deterministic patterns may be fabricated with desired functions, e.g., lotus effect (hydrophobic), gecko feet (adhesive), haptic tactile, etc. The objective of this review is to explore the surface texturing technology and its contributions to the applications., Railway Engineering

Het doel van het project was de ontwikkeling van een codegenerator om snel nieuwe webprojecten op te kunnen starten. Het bedrijf Fenêtre ontwikkelt complexe internetapplicaties met behulp van een eigen framework. De projecten die met dit framework, Silicon 5, worden gemaakt bevatten vaak project-specieke entiteiten. Voor deze entiteiten zijn bijna altijd onderhoudsschermen nodig. Elk project is uniek, daarom zullen deze schermen voor elk project op een andere manier gebouwd moeten worden. Dit is een tijdrovend proces. Omdat alle schermen volgens dezelfde structuur zijn gemaaktkan het bouwen van de schermen signicant versneld worden met een codegenerator. De uitdaging zat in het zo goed mogelijk benutten van de beschikbare informatie over de tabellen in het framework. Door een reeds bestaande generator is van elke databasetabel een model gemaakt. De combinatie van de metadata uit de database en de beschikbare modellen, biedt veel mogelijkheden. Voornamelijk het analyseren en genereren van de elementen voor relaties tussen verschillende tabellen en views (en dus tussen schermen) is een uitdaging. Samen met het bedrijf zijn op dit gebied veel complexe problemen bediscussieerd en aangepakt. Het eindproduct is een volledig werkende applicatie die aan bijna alle gestelde eisen voldoet. De ap-plicatie biedt de mogelijkheid om met enkele klikken een serie schermen te genereren op basis van een databasetabel. Deze nieuwe schermen zijn daarna direct te gebruiken in de webapplicatie, inclusief bijkomende functionaliteiten zoals het bewerken van data. Wensen en mogelijkheden die tijdens het project zijn ontdekt, zijn geformuleerd in een lijst van aanbevelingen. De ontwikkelaars bij Fenêtre zullen deze generator gaan gebruiken bij het opstarten van projecten. Een aantal schermen die standaard in het framework zitten, zijn zelfs al gemaakt met de generator. Daarnaast zal de generator ook met zekerheid nog verder uitgebreid worden met extra functionaliteiten., Bachelor Project, Computer Science, Electrical Engineering, Mathematics and Computer Science

Aluminium bronze, well known for its good sliding properties, is frequently applied as tool material in sheet metal forming (SMF) of stainless steel, e.g. for the production of washing, refrigeration and cooking equipment. The limited hardness of the material makes it, however, sensitive to tool wear that is: volumetric wear of the tool due to sliding contact with the sheet material. Conventional wear tests like the rubber wheel abrasion test or the Taber abrader test cannot be used to simulate the interaction of the tooling with lubricated sheet material. Dedicated tribo tests are therefore conducted with the slider-on-sheet test. The aim of the research is to measure the specific wear rate of aluminium bronze at SMF-like conditions. Experimental results showed a pronounced influence of lubricant selection and sheet material selection. The measured specific wear rate varied from 10(-8) mm(3)/N m for a smooth stainless steel sheet quality to 10(-6) mm(3)/N m for a rough surface quality., QC 20130522