Pohang Canal Dataset: A Multimodal Maritime Dataset for Autonomous Navigation in Restricted Waters

This paper presents a multimodal maritime dataset and the data collection procedure used to gather it, which aims to facilitate autonomous navigation in restricted water environments. The dataset comprises measurements obtained using various perception and navigation sensors, including a stereo camera, an infrared camera, an omnidirectional camera, three LiDARs, a marine radar, a global positioning system, and an attitude heading reference system. The data were collected along a 7.5-km-long route that includes a narrow canal, inner and outer ports, and near-coastal areas in Pohang, South Korea. The collection was conducted under diverse weather and visual conditions. The dataset and its detailed description are available for free download at https://sites.google.com/view/pohang-canal-dataset.Comment: Submitted to IJRR as a data paper for revie

Effect of rubber interlayers on the fracture of glass bead/epoxy composites

The effectiveness of rubber interlayers between inorganic particles and polymer matrix for toughening has been a controversial subject. In this research, a series of rubber-encapsulated glass beads and its epoxy composites were prepared, and underlying mechanisms which can connect material parameters related with rubber interlayers with energy dissipation mechanisms, were investigated. The critical stress intensity factor ( K IC ) and critical strain energy release rate ( G IC ) of rubber-encapsulated glass bead filled epoxies were found to insignificantly depend on the existence and thickness of rubber interlayers. Microscopy studies on fracture process identified four different micro-mechanical deformations which can dissipate fracture energy: step formation, micro-shear banding, debonding of glass beads, and diffuse matrix shear yielding. It was found that the first two became less extensive and the others became more extensive as the thickness of rubber interlayers increases. This offsetting effect of micro-mechanical deformations seems to be the reason for the absence of significant toughening effect of rubber interlayers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44764/1/10853_2004_Article_318304.pd

Surface tailored PS/TiO2 composite nanofiber membrane for copper removal from water

none8siPolystyrene (PS)/TiO2 composite nanofiber membranes have been fabricated by electrospinning process for Cu2+ ions removal from water. The surface properties of the polystyrene nanofibers were modulated by introducing TiO2 nanoparticles. The contact angle of the PS nanofiber membrane was found to be decreased with increasing concentration of TiO2, depicted enhanced hydrophilicity. These membranes were highly effective in adsorbing Cu2+ ions from water. The adsorption capacity of these membranes was found to be 522 mg/g, which is significantly higher than the results reported by other researchers.This was attributed to enhanced hydrophilicity of the PS/TiO2 composite nanofiber membranes and effective adsorption property of TiO2 nanoparticles.noneWanjale, Santosh; Birajdar, Mallinath; Jog, Jyoti; Neppalli, Ramesh; Causin, Valerio; Karger-Kocsis, József; Lee, Jonghwi; Panzade, PrasadWanjale, Santosh; Birajdar, Mallinath; Jog, Jyoti; Neppalli, Ramesh; Causin, Valerio; Karger Kocsis, József; Lee, Jonghwi; Panzade, Prasa

Electrothermal soft manipulator enabling safe transport and handling of thin cell/tissue sheets and bioelectronic devices

“Living” cell sheets or bioelectronic chips have great potentials to improve the quality of diagnostics and therapies. However, handling these thin and delicate materials remains a grand challenge because the external force applied for gripping and releasing can easily deform or damage the materials. This study presents a soft manipulator that can manipulate and transport cell/tissue sheets and ultrathin wearable biosensing devices seamlessly by recapitulating how a cephalopod’s suction cup works. The soft manipulator consists of an ultrafast thermo-responsive, microchanneled hydrogel layer with tissue-like softness and an electric heater layer. The electric current to the manipulator drives microchannels of the gel to shrink/expand and results in a pressure change through the microchannels. The manipulator can lift/detach an object within 10 s and can be used repeatedly over 50 times. This soft manipulator would be highly useful for safe and reliable assembly and implantation of therapeutic cell/tissue sheets and biosensing devices

Inorganic particle toughening: The fracture and toughening mechanism of glass bead filled epoxies.

The incorporation of inorganic particles into polymeric matrices is a widely used method for toughening and stiffening polymers, but is poorly understood at a mechanistic level. By using glass bead filled epoxies, the effects of various material parameters, such as volume fraction, size, surface treatments of glass beads, and inherent matrix toughness, on the fracture toughness of composites were studied. To understand the relationship between the fracture toughness and the various material parameters, the micro-deformation processes occurring during fracture are identified and their contributions to toughening evaluated. Among these processes, micro-shear banding within the matrix was found to play a major role. By promoting this process through changes in the matrix ductility, the fracture energy of composites has been increased by as much as 340% over that of the unmodified epoxy using just 10 vol% of glass beads. Moreover, a possible explanation is also given for the lack of success of previous efforts to toughen these materials by changing interfacial strength. In addition to the study on glass bead filled epoxies, hybrid-particulate composites based on glass beads, rubber particles, and epoxy resin were prepared and their fracture behavior was investigated. An increase in fracture toughness by the incorporation of glass beads and rubber particles could be explained by combining the micro-shear banding mechanism of glass beads and the cavitation/matrix shear yielding mechanism of rubber particles.Ph.D.Applied SciencesChemical engineeringMaterials scienceMechanicsPlasticsPolymer chemistryPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/131469/2/9909929.pd

Mimicking Neuromuscular Junctions Using Controlled Crystallization of Solvents: A Surface and Interface Engineering Technique for Polymers

Recently, crystallization engineering has become a novel processing technique for various materials, including ceramics, polymers, and composites. Herein, a novel processing technology of polymers based on controlled directional crystallization was developed for biomimetic surfaces and interfaces. Solvent was allowed to come into contact with a polymer surface for a limited time, followed by controlled crystallization of the solvent along a temperature gradient perpendicular to the surface. As a result, perpendicular pores of well-defined patterns were successfully prepared, as well as adhesive-free strong interfaces mimicking neuromuscular junctions. By increasing the temperature of the polymer or solvent contact time, the pore depth and contact angle increased. Highly hydrophobic surfaces of polycarbonate were efficiently prepared, and interfacial adhesion with polydimethylsiloxane was improved by more than 4-fold. This novel processing technique based on crystal engineering could open completely new application possibilities, particularly for biomedical devices, soft lithography, microfabrication, soft sensors, and flexible and stretchable electronics

3D Cocontinuous Composites of Hydrophilic and Hydrophobic Soft Materials: High Modulus and Fast Actuation Time

Hydrogels in nature seldom form a single phase, more often forming structured phases with other soft phases, allowing nature to develop responsive and adaptive strategies. Based on knowledge of how hydrogels are utilized in nature, we developed novel 3D cocontinuous composites from soft materials with extremely different properties, a hydrogel and a silicone. These were successfully prepared by infiltrating liquid polydimethylsiloxane (PDMS) into poly­(<i>N</i>-isopropylacrylamide) (PNIPAm) frameworks of aligned pores prepared by directional melt crystallization. The composites had outstanding modulus and swelling ratio compared to other mechanically strong hydrogels. More interestingly, the deswelling kinetics were dramatically accelerated (by a factor of 1000), possibly due to the aligned microchannels and the hydrophobic nature of PDMS. As a result, an actuator movement mimicking flowering could be completed in less than 20 s. This novel and versatile cocontinuous composite strategy could overcome the current limitations of soft materials