A study on magnetic abrasive deburring of dual micro pattern

Studies on dual micro pattern are not established because of difficulty of its fabrication and deburring technology. In this investigation, a dual micro pattern which consists of a net pattern and a lenticular pattern was fabricated on a cylindrical workpiece by turning process. Magnetic abrasive deburring (MAD) was proposed as a deburring process in this study. Burr height defined by difference of its height and theoretical pattern height was measured as about 1 μm. It is one of the non-traditional machining methods utilizing flexible tool which consists of ferrous particle and abrasive powder. Hence, the aim of this investigation is to remove generated burr on the dual micro pattern. Burr at the dual micro pattern was removed through MAD, and a prediction equation of machined pattern height was derived. A deburring condition was optimized and verified by experiments. As a result, it was confirmed that dual micro pattern which has high shape accuracy was fabricated using MAD.

     

Model test assessment of the generation of underground cavities and ground cave-ins by damaged sewer pipes

Ground cave-ins caused by damaged sewer pipes have been frequently reported in metropolitan areas and have caused severe socioeconomic losses. In this study, model experiments were conducted to determine how damaged sewer pipes generate ground cave-ins or cavities, with a focus on the influence of the soil type and density. Digital images of the model ground were captured to evaluate the internal deformation of the model grounds. Additionally, the vertical displacement at the surface, the size of the cavity, and the weight of the discharged soil were measured in each test. The results indicate that uniform soil with no fines content was more vulnerable to ground cavities than well-graded soil with fines content. Loose soil led to a ground cave-in with significant deformation over the entire model ground, whereas deformation was concentrated only on the ground cavities in the dense soil ground.     

Nanoscale adhesion,friction and wear studies of biomolecules on silane polymer-coated silica and alumina-based surfaces

Proteins on biomicroelectromechanical systems (BioMEMS) confer specific molecular functionalities. In planar FET sensors (field-effect transistors, a class of devices whose protein-sensing capabilities we demonstrated in physiological buffers), interfacial proteins are analyte receptors, determining sensor molecular recognition specificity. Receptors are bound to the FET through a polymeric interface, and gross disruption of interfaces that removes a large percentage of receptors or inactivates large fractions of them diminishes sensor sensitivity. Sensitivity is also determined by the distance between the bound analyte and the semiconductor. Consequently, differential properties of surface polymers are design parameters for FET sensors. We compare thickness, surface roughness, adhesion, friction and wear properties of silane polymer layers bound to oxides (SiO₂ and Al₂O₃, as on AlGaN HFETs). We compare those properties of the film–substrate pairs after an additional deposition of biotin and streptavidin. Adhesion between protein and device and interfacial friction properties affect FET reliability because these parameters affect wear resistance of interfaces to abrasive insult in vivo. Adhesion/friction determines the extent of stickage between the interface and tissue and interfacial resistance to mechanical damage. We document systematic, consistent differences in thickness and wear resistance of silane films that can be correlated with film chemistry and deposition procedures, providing guidance for rational interfacial design for planar AlGaN HFET sensors.     

Laser diffraction particle sizing by wet dispersion method for spray-dried infant formula

A laser diffraction particle sizing method involving wet analysis could be adapted effectively to measure the accurate particle size distribution of a spray-dried infant formula. Polar, polar aprotic and non-polar solvents, such as ethanol, methanol, acetone, pentane, heptane and hexane, were tested as dispersants for wet analysis. Non-polar solvents such as pentane, heptane and hexane found to be suitable dispersant because the shape of the infant formula particles in non-polar solvents was similar before and after the measurement while the particles had dissolved in the other solvents. The particle size distributions (PSD) of the infant formula determined by laser diffraction (Malvern Master Sizer, UK) using the dry analysis method with air was unsuitable because some parts of the primary and aggregated infant formula particles had been destroyed. The PSD graph of the air dispersion was shifted toward a smaller particle size from that of hexane dispersion. Overall, it is believed that laser diffraction particle sizing involving wet analysis with non-polar solvents may provide a suitable particle sizing method for infant formula products that is better than an air dispersion method.     

Improved Emotion Recognition With a Novel Speaker-Independent Feature

Emotion recognition is one of the latest challenges in human-robot interaction. This paper describes the realization of emotional interaction for a Thinking Robot, focusing on speech emotion recognition. In general, speaker-independent systems show a lower accuracy rate compared with speaker-dependent systems, as emotional feature values depend on the speaker and their gender. However, speaker-independent systems are required for commercial applications. In this paper, a novel speaker-independent feature, the ratio of a spectral flatness measure to a spectral center (RSS), with a small variation in speakers when constructing a speaker-independent system is proposed. Gender and emotion are hierarchically classified by using the proposed feature (RSS), pitch, energy, and the mel frequency cepstral coefficients. An average recognition rate of 57.2% (plusmn 5.7%) at a 90% confidence interval is achieved with the proposed system in the speaker-independent mode.     

Aspergillus oryzae strains isolated from traditional Korean Nuruk: Fermentation properties and influence on rice wine quality

Forty-seven strains of Aspergillus oryzae isolates from Korean nuruks were compared for their brewing characteristics. A. oryzae YI-A6 and YI-A7 showed the highest acid α-amylase, glucoamylase, and carboxypeptidase activities, respectively. Sixteen isolates with high amylolytic or proteolytic enzyme activities were selected for investigation of their rice wine fermentation characteristics. After 12 days of brewing at 15°C, ethanol concentrations were 10.2–14.3% for A. oryzae strains. Fermentation rates were the highest for YI-A7. Most rice wine samples fermented with nuruk strains had lower concentrations of off-flavor compounds than the control did. All mean sensory attribute values significantly differed among samples. Pearson correlation coefficients showed that glucoamylase activity was positively correlated to both ethanol productivity and overall harmony (p<0.01). Thus, glucoamylase activity was identified as the best factor for screening Aspergillus strains for use in rice wine brewing.     

Correlation of Microstructure and Cracking Phenomenon Occurring during Hot Rolling of Lightweight Steel Plates

An investigation was conducted into the correlation of microstructure and the cracking phenomenon that often occurred in hot-rolled lightweight steel plates. Two kinds of steels were fabricated with varying Mn and Al contents, and their microstructures, tensile properties, and high-temperature transformation behavior were investigated. In the two steels, banded structures containing ferrite grains and κ-carbides were well developed along the rolling direction. Detailed microstructural analyses showed that cracks initiated at film-type κ-carbides continuously formed interfaces between bands, while the band populated with κ-carbides did not play an important role in initiating cracks. Thus, the formation of band structures and film-type interfacial κ-carbides must be minimized to prevent the cracking. The decreased content of hardenability elements, including aluminum, higher finish-rolling temperature, reduced central segregation during the slabmaking process, and decreased material variation during hot rolling, were suggested as practical methods for preventing the cracking.     

Poly(lactic acid) blends with desired end-use properties by addition of thermoplastic polyester elastomer and MDI

The disadvantages of the poor mechanical properties of polylactic acid (PLA) limit its ability to be used in a wide number of applications. Melt blending of PLA and thermoplastic polyester elastomer (TPEE) has been performed in an effort to toughen the PLA without significant losses in modulus and ultimate tensile strength. In order to enhance the compatibility of PLA and TPEE, a diisocyanate compound was used as a reactive modifier. The thermal and mechanical properties, miscibility and phase morphologies of the blends were investigated. A blend of PLA and TPEE with a modifier does not lead to an important drop in tensile strength and modulus whereas the elongation at break is characterized by a significant increase (above 300%), compared with that of neat PLA and PLA/TPEE. The blends of PLA/TPEE/Modifier were found by thermal and fractured surface analysis to be an immiscible system with the addition of a modifier. However, the relative ductility of PLA/TPEE/Modifier is 34 times higher than that of neat PLA. The brittle fracture of neat PLA was transformed into a ductile fracture by the addition of a modifier.