An inert gas such as nitrogen is used as an extinguishing agent to suppress unexpected fire in places such as computer rooms and server rooms. The gas released with high pressure causes noise above 130 dB. According to recent studies, loud noise above 120 dB has a strong vibrational energy that leads to a negative influence on electronic equipment with a high degree of integration. In this study, a basic fire-extinguishing nozzle with absorbent was selected as the reference model, and numerical analysis was conducted using the commercial software, ANSYS FLUENT ver. 18.1. A total of 45 experiment points was selected using the design of experiment (DOE) method. An optimum point was derived using the response surface method (RSM). Results show that the vibrational energy of the noise was reduced by minimizing the turbulence kinetic energy. Pressure and velocity distributions were calculated and graphically depicted with various absorbent configurations.
Increasing concerns over green farming technology, plant growth promoting rhizobacterium (PGRP) having growth promoting as well as plant disease suppressing properties was recently preferred to use for biological control of plant pathogens infecting plant. We measured the influence of the selected microbial consortium agents-a mixture of PGPR strains-, commercial biofungicide, and chemical pesticides on soil microbial community in red pepper field. The activities of soil enzyme such as dehydrogenase, urease, phosphatase, β-glucosidase, and cellulase were analyzed to investigate that of soil microbial community. We also measured plant length, main stem, stem diameter, number of branches and yields of red-pepper in order to observe the red pepper growth promotion. The results of measuring enzyme activities were dehydrogenase 3.5584 µg TPF g
Fire extinguishing systems are essential equipment in all indoor facilities to address unexpected fire scenarios, and appropriate fire extinguishing agent should be used depending on the place and object to protect. Among these, gaseous fire-extinguishing systems are used to protect electronic equipment. Therefore, inert gases that do not undergo chemical reactions are used mainly in those systems. On the other hand, recently, owing to the high integration of electronic equipment, there are some cases, in which large noise generated from gaseous systems damage the electronic equipment. In this study, numerical analysis of the discharge noise with various nozzle contraction angles was carried out to improve the gas fire extinguishing system. Numerical analysis was carried out using ANSYS FLUENT ver 18.1. The causes of the noise were elucidated using the swirl distribution. The noise level of the modified model was reduced by approximately 6 dB compared to the reference model, which is similar to the result of a previous study, confirming the validity of the method.
The intensive cropping of red pepper (Capsicum annuum L.) negatively affects the soil environment and reduces crop yield. The red pepper plant's rhizospheric bacterial communities under different cropping methods (intensive cropping or crop rotation) were investigated over three years (2010 to 2012). The red pepper yield and bacterial communities were also investigated under agrochemical treatment or microbial agent treatment against Phytophthora blight disease. Pyrosequencing of 16S rRNA gene amplicon libraries were constructed to characterize the bacterial communities. Bacterial richness and red pepper yield increased 65% and 55%, respectively under the crop rotation method combined with the microbial agent treatment, whereas the intensive cropping method with the agrochemical treatment resulted in low richness and diversity. The dominant bacterial phylogenetic phyla present were Acidobacteria, Proteobacteria, Gemmatimonadetes, Chloroflexi, and Planctomycetes, ranging from 5% to 38% of the sequences. In conclusion, crop rotation and microbial agent has a synergistic positive effect not only on rhizobacterial diversity, but also on red pepper yield.
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