Categorical formulation of mathematical design theories applied to system design process analysis

Given hierarchical system specifications, embodiment and integration processes of subsystems are crucial in designing complex engineered systems. To complement the current mathematical design theories that do not sufficiently support these processes, this study applies general design theory to formulate these processes based on the mathematical structure of design knowledge studied in the literature using category theory. Specifically, the composition of embodiment operations and the relations among subsystems in integration operations on the category of sets and topological spaces are elucidated. Furthermore, the formulation is applied to analysis of a system design process of a production line in model-based systems engineering.     

A TEM study on melt-crystallized poly(butylene terephthalate)

A study was made to investigate an optimum condition for ruthenium tetraoxide staining of poly(butylene terephthalate) (PBT) with glass transition temperature as low as ca. 23 degrees C for TEM observation of melt-grown PBT crystals. The morphological study of ultrathin sections prepared based on optimum staining at 25 degrees C for 8 h revealed formation of fringed-micellar crystal nuclei in the early stage and folded-chain fringed-micellar crystals in the later stage of isothermal crystallization at 40 degrees C from melt. The fraction of chain-folded crystals increased with increasing crystallization temperature from the quantitative analysis of crystal thickness in comparison with the reported morphology using the replica method.     

Catalytic Friedel–Crafts Acylation of Heteroaromatics

Catalytic Friedel–Crafts acylation of heteroaromatics has been achieved using metal triflates as catalysts. While conventional Friedel–Crafts acylation often requires the use of more than stoichiometric amounts of aluminum chloride, metal triflates such as tin(II) triflate, scandium triflate, and gallium triflate, etc. have enabled efficient acylation reactions by catalytic use.     

Effect of arbutin on melanogenic proteins in human melanocytes

OBJECTIVE: Peritonsillar sepsis (PTS) can be divided into abscess and cellulitis. It is the most common deep neck infection in the paediatric age group. In this article we discuss the clinical issues related to peritonsillar sepsis in children. METHOD: This study involves 185 cases of peritonsillar that were treated at the Montreal Children's Hospital in the last 10 years. The symptoms, signs, laboratory and radiological data as well as the medical and surgical therapies are included. RESULTS: Seventy-five cases were peritonsillar cellulitis (PTC) and the rest were abscesses. The age at presentation varied between 2.5 months and 18 years. The majority of the cases diagnosed as peritonsillar abscess (PTA) occurred from age 12 to 18 years. Trismus was the only complaint that was statistically associated with PTA. Uvular deviation combined with trismus was also important in differentiating PTA from PTC. Our data revealed a lower percentage of anaerobic bacteria and the majority of cultures grew Streptococcus pyogenes group A. CONCLUSIONS: Clinical picture is important in differentiating PTA from PTC. Recurrence of peritonsillar sepsis was higher in children with a history of recurrent tonsillitis. Needle aspiration of PTA resulted in a higher incidence of recurrence compared to incision and drainage. A management algorithm is suggested for the child presenting with peritonsillar sepsis.     

A life-cycle analysis on thin-film CdS/CdTe PV modules

Authors have evaluated the life cycle of a thin-film CdS/CdTe PV module to estimate the energy payback time (EPT) and the life-cycle CO₂ emissions of a residential rooftop PV system using the CdS/CdTe PV modules. The primary energy requirement for producing 1 m² of the CdS/CdTe PV module was similar to a-Si PV module at annual production scale of 100 MW. EPT was calculated at 1.7–1.1 yr, which was much shorter than the lifetime of the PV system and similar to that of a-Si PV modules. The life-cycle CO₂ emissions were also estimated at 14–9 g-C/kWh, which was less than that of electricity generated by utility companies.     

Prediction of Bending Fatigue Life of Cracked Out-of-Plane Gusset Joint Repaired by CFRP Plates

Carbon fiber reinforced polymer (CFRP), plates bonding repair method is one of the simple repair methods for cracked steel structures. In this study, the influence of width of CFRP plates on bending fatigue life of out-of-plane gusset joint strengthened with CFRP plates was investigated from the experimental and numerical point of view. In the bending fatigue test of cracked out-of-plane gusset joint strengthened with CFRP plates, the effect of width of CFRP plates on crack growth life was clarified experimentally. Namely, it was revealed that the crack growth life becomes larger with increasing the width of CFRP plates. In the numerical approach, the stress intensity factor (SIF) at the surface point of a semi-elliptical surface crack was estimated based on the linear fracture mechanics. Furthermore, the extended fatigue life of cracked out-of-plane gusset joint strengthened with CFRP plates was evaluated by using the estimated SIF at the surface point and the empirical formula of the aspect ratio of semi-elliptical crack. As the results of numerical analysis, the estimated fatigue life of the specimen strengthened with CFRP plates showed the good agreement with the test results.     

Morphology of melt-crystallized syndiotactic polypropylene

A transmission electron microscopy (TEM) study was made to investigate the mechanism of isothermal crystallization from melt for syndiotactic polypropylene (sPP) with a syndiotactic pentad fraction of 0.92. The TEM morphologies of RuO4-stained and ultrathin-sectioned specimens revealed a clear assignment of lamellar crystals with different crystal thicknesses to their corresponding melting temperatures and types of crystal structures. It has been found that isolated, single crystal lamellae with cell III structure were grown at 140 degrees C by a plausible crystal growth mechanism with regime I. Fringed-micellar type of lamellae with cell II structure as thin as c. 4 nm were formed in the interstices of the thick chain-folded lamellae by the subsequent quenching.