Case study: Noise reduction of a vacuum-assisted toilet

Flushing a vacuum-assisted toilet generates noise levels that can be disturbing both to users and those nearby. Peak radiated noise levels correlate with the time when the valve opens and closes, while the noise levels when the valve is com- pletely open are also relatively high. Significant noise ranges between 300 Hz and 3000 Hz. It was hypothesized that increasing the in-tube distance between the flush valve and the bowl in addition to increasing the bend radius of the tube would reduce radiated noise levels. These modifications resulted in a reduction of about 14 dB in the radiated noise during the valve opening and closing in ad- dition to a reduction of about 5 dB while the valve is completely opened. Inter- mediate results of varying the tube length and bend radius are presented to show their effects on the radiated sound levels. Two tube inserts were designed to fit (1) underneath and (2) behind the toilet in a compact manner. They were tested to show that they maintain noise control performance without modifying any other part of the toilet.

Pulling Simulations and Hydrogen Sorption Modelling on Carbon Nanotube Bundles

Recent progress in molecular simulation technology has developed an interest in modernizing the usual computational methods and approaches. For instance, most of the theoretical work on hydrogen adsorption on carbon nanotubes was conducted a decade ago. It should be insightful to reinvestigate the field and take advantage of code improvements and features implemented in contemporary software. One example of such features is the pulling simulation modules now available in many molecular dynamics programs. We conduct pulling simulations on pairs of carbon nanotubes and measure the inter-tube distance before they dissociate in water. We use this distance to set the interval size between adjacent nanotubes as we arrange them in bundle configurations. We consider bundles with triangular, intermediate and honeycomb patterns, and armchair nanotubes with a chiral index from n = 5 to n = 10. Then, we simulate low pressure hydrogen adsorption isotherms at 77 K, using the grand canonical Monte Carlo method. The different bundle configurations adsorb great hydrogen amounts that may exceed 2% wt at ambient pressures. The computed hydrogen capacities are considered large for physisorption on carbon nanostructures and attributed to the ultra-microporous network and extraordinary high surface area of the configured models.

Mechanical and Electroconductive Properties of Mono- and Bilayer Graphene–Carbon Nanotube Films

This article presents the results of a computer study of electrical conductivity and deformation behavior of new graphene–carbon nanotube (CNT) composite films under bending and stretching. Mono- and bilayer hybrid structures with CNTs (10,0) and (12,0) and an inter-tube distance of 10 and 12 hexagons were considered. It is revealed that elastic deformation is characteristic for mono- and bilayer composite films both in bending and stretching. It is found that, in the case of bending in a direction perpendicular to CNTs, the composite film takes the form of an arc, and, in the case of bending in a direction along CNTs, the composite film exhibits behavior that is characteristic of a beam subjected to bending deformation as a result of exposure to vertical force at its free end. It is shown that mono- and bilayer composite films are more resistant to axial stretching in the direction perpendicular to CNTs. The bilayer composite films with an inter-tube distance of 12 hexagons demonstrate the greatest resistance to stretching in a direction perpendicular to CNTs. It is established that the CNT diameter and the inter-tube distance significantly affect the strength limits of composite films under axial stretching in a direction along CNTs. The composite films with CNT (10,0) and an inter-tube distance of 12 hexagons exhibit the highest resistance to stretching in a direction along CNTs. The calculated distribution of local stresses of the atomic network of deformed mono- and bilayer composite films showed that the maximum stresses fall on atoms forming covalent bonds between graphene and CNT, regardless of the CNT diameter and inter-tube distance. The destruction of covalent bonds occurs at the stress of ~1.8 GPa. It is revealed that the electrical resistance of mono- and bilayer composite films decreases with increasing bending. At the same time, the electrical resistance of a bilayer film is 1.5–2 times less than that of a monolayer film. The lowest electrical resistance is observed for composite films with a CNT (12,0) of metallic conductivity.

Morphometric study of cervical spine vertebrae in eastern region Nepalese population

Objective: To ascertain the normal values of mid-sagittal vertebral body Diameter, mid-sagittal canal diameter and canal-body ratio in adult Nepalese population. Methods: In this consent based descriptive, clinico -radiological study of 100 individuals who volunteered to being subjected to lateral projection radiographs of cervical spine. The sagittal canal diameter (CD), sagittal vertebral body diameter (VBD) and the canal-body ratio (CBR) was recorded on lateral projection radiographs (film to tube distance at 183 cms) and analyzed statistically. Results: The mean vertebral body diameter was 17.81±1.73mm (male:18.30±1.64mm;female:17.05±1.61mm), mean canal diameter was 17.18±1.67mm (males:17.31±1.74mm; females: 16.97±1.56mm),the mean canal body ratio was 0.97±0.13 (males:0.95±0.13; females:1.00±0.13). In mongoloids mean body diameter is 18.23±1.58 mm, mean canal diameter is 16.87±1.77 mm. and mean canal body ratio is 0.93±0.13. In non-mongoloids the mean body diameter was 17.48±1.79 mm, mean canal diameter was 17.42±1.59 mm, and mean canal body ratio was 1.00±0.13. Conclusion: The vertebral body diameter was significantly larger in men as compared to women, and this difference was statistically significant at all vertebral levels (p <0.05). The canal diameter was more in males than females but this difference was not statistically significant (p >0.05). The canal body ratio was greater in females than in males at all levels but this was also not statistically significant (p >0.05. The canal diameter was more in non-mongoloids as compared to mongoloids but this difference was not significant except at C2 level. Population in the eastern region of Nepal had values more nearer to Indian population but lesser than Europeans. DOI: http://dx.doi.org/10.3126/hren.v11i3.9636 Health Renaissance 2013;11(3):224-228

Effects of Tube Space on the Thermal Performance of Water-in-Glass Evacuated Tube Solar Water Heaters

In the present specification of domestic solar water heating systems (GB/T19141), regardless of the type of collectors used in the systems, Q17, the daily heat gain corresponding to the daily radiation of 17MJ/m2 on the collector surface, is a key indication to rate the thermal performance of a domestic solar water heaters. In this work, an attempt was made to investigate effect of the distance between two adjacent tubes in solar tube collectors of a water-in-glass evacuated tube solar water heater (ETSWH) on by theoretical calculations and experimental measurements. Results obtained by simulations and experimental test showed that the tube space had a significant effect on of the ETSWH, the shorter the tube distance, the higher the Q17, thus better the ETSWH performs. However, the actual situation is the case, the shorter the tube distance, the lower the real daily solar gain of the system, thus worse it performs. This implied that Q17 as the indication of thermal performance of the ETSWH is not reasonable, and specifying the tube distance in solar tube collectors of the ETSWH in the technical specification of GB/T19141 is advisable so as to eliminate effect of the tube distance on Q17.

Delineation of the three brown rot fungi of fruit crops (Monilinia spp.) on the basis of quantitative characteristics

The three Monilinia spp., known as the brown rot fungi of fruit crops, are usually distinguished from each other on the basis of (qualitative) colony characteristics. We linked these qualitative features to unambiguously defined, quantitative colony and germ tube characteristics. A wide collection of isolates of Monilinia fructicola (Winter) Honey, Monilinia laxa (Aderhold & Ruhland) Honey, and Monilinia fructigena (Aderhold & Ruhland) Honey was used to determine growth rate and sporulation intensity on potato dextrose agar (PDA) at 22°C under two light regimes (darkness, 12 h light : 12 h dark). The following germ tube characteristics were determined on water agar after incubation for 18 h at 22°C in darkness: length of the (leading) germ tube, distance to the first branch, and the number of germ tubes per conidium. Increase in colony diameter from day 3 to day 5 and sporulation intensity measured after 14 days was the highest in M. fructicola, whilst M. laxa and M. fructigena showed considerable overlap in these features. The length of the germ tube after 18 h incubation was shortest in M. laxa, ranging from 161 to 466 µm. In M. fructicola and M. fructigena these ranges were 465-851 and 307-806 µm, respectively. The occurrence of more than one germ tube per conidium was most prominent in M. fructigena. Discriminant analysis on the basis of different combinations of the quantitative characteristics measured, showed that the combination of growth rate on PDA and length of the germ tube was sufficient to delineate the three brown rot fungi. One of 11 M. fructicola isolates was misclassified, the same held for M. fructigena (one misclassification of nine isolates). No misclassifications occurred in M. laxa.Key words: brown rot fungi, growth characteristics, Monilinia spp., taxonomy.