Abslract--Summarized are recent experimental findings of fire spread phenomena. This review cover... more Abslract--Summarized are recent experimental findings of fire spread phenomena. This review covers flame spread over solids (including melting solids and metals), large-scale spread through discrete fuels (such as fire brands and fire whirls), and scale modeling techniques applied to flame spread study. Emphasis is placed on the importance of observation in experiments which is the source of imagination and successful modeling.
It is well documented that applying mechanical vibration to the mold during solidification has a ... more It is well documented that applying mechanical vibration to the mold during solidification has a profound effect on the microstructure and mechanical properties of castings. However, it is still not well understood how mechanical vibration change the resulting microstructure. Most of the available studies are qualitative and provide little quantitative information that can be used by the casting industry. In this work, mechanical mold vibration is applied to an Al-Si eutectic (Al-12.5% Si) alloy at a frequency of 100 Hz and variable amplitudes in the range of 18-199 m. It is shown that the silicon morphology was strongly influenced by the level of vibration amplitude. Generally, increasing the vibration amplitude tends to reduce the lamellar spacing and change the silicon morphology to become more fibrous. However, exceeding a critical value of vibration amplitude tends to coarsen the silicon. The corresponding changes in mechanical properties are also investigated. It is shown that the maximum elongation is more influenced by vibration than the tensile strength for the range of conditions tested here.
Measured temperature and composition profiles are reported for a number of flames. Implications c... more Measured temperature and composition profiles are reported for a number of flames. Implications concerning flame structure are deduced, with emphasis on soot formation and on correlation involving conserved scalars.
We previously showed that infrared thermography (IRT) could be used to quantify viable Escherichi... more We previously showed that infrared thermography (IRT) could be used to quantify viable Escherichia coli, a representative gram-negative bacterium, in liquid growth media. Here, we evaluated the ability of IRT to enumerate a viable representative gram-positive organism, Staphylococcus aureus. We found that the energy content (EC) of the media was strongly positively correlated (r = 0.999) to measured viable counts of S. aureus ranging from 85 colony-forming units (CFU)/ml to $4 Â 10 8 CFU/ml. The EC of S. aureus was $2-fold higher than that of E. coli at comparable cell concentrations suggesting that IRT may be used to distinguish genera.
Quantifying viable bacteria in liquids is important in environmental, food processing, manufactur... more Quantifying viable bacteria in liquids is important in environmental, food processing, manufacturing, and medical applications. Since vegetative bacteria generate heat as a result of biochemical reactions associated with cellular functions, thermal sensing techniques, including infrared thermography (IRT), have been used to detect viable cells in biologic samples. We developed a novel method that extends the dynamic range and improves the sensitivity of bacterial quantification by IRT. The approach uses IRT video, thermodynamics laws, and heat transfer mechanisms to directly measure, in real-time, the amount of energy lost as heat from the surface of a liquid sample containing bacteria when the specimen cools to a lower temperature over 2 min. We show that the Energy Content (EC) of liquid media containing as few as 120 colony-forming units (CFU) of Escherichia coli per ml was significantly higher than that of sterile media (P < 0.0001), and that EC and viable counts were strongly positively correlated (r = 0.986) over a range of 120 to approximately 5 Â 10 8 CFU/ml. Our IRT approach is a unique non-contact method that provides real-time bacterial enumeration over a wide dynamic range without the need for sample concentration, modification, or destruction. The approach could be adapted to quantify other living cells in a liquid milieu and has the potential for automation and high throughput.
The effects of magnetic field on the microgravity combustion characteristics of a single methanol... more The effects of magnetic field on the microgravity combustion characteristics of a single methanol droplet in homogeneous flow are numerically investigated to develop an effective magnetic control method for microgravity droplet combustion and spray combustion systems. First, governing equations of microgravity single methanol droplet combustion under a homogeneous magnetic field based on an unsteady two-dimensional, spherically symmetric model including single-step chemistry are presented. Employing numerical modeling, several combustion behaviors are calculated taking into account the effect of the unsteady magnetic field profiles at the flame front. It is found that the flame front becomes deformed and is elongated in the direction of the magnetic field due to the inhomogeneous magnetic pressure distribution at the interface between the fuel vapor phase and the oxidizer phase. This nonuniformity of magnetic pressure is caused by the transient deformation of the magnetic field with refraction of magnetic flux at the flame front due to the difference of magnetic susceptibility between the diamagnetic fuel vapor phase and the paramagnetic oxidizer phase.
Abslract--Summarized are recent experimental findings of fire spread phenomena. This review cover... more Abslract--Summarized are recent experimental findings of fire spread phenomena. This review covers flame spread over solids (including melting solids and metals), large-scale spread through discrete fuels (such as fire brands and fire whirls), and scale modeling techniques applied to flame spread study. Emphasis is placed on the importance of observation in experiments which is the source of imagination and successful modeling.
It is well documented that applying mechanical vibration to the mold during solidification has a ... more It is well documented that applying mechanical vibration to the mold during solidification has a profound effect on the microstructure and mechanical properties of castings. However, it is still not well understood how mechanical vibration change the resulting microstructure. Most of the available studies are qualitative and provide little quantitative information that can be used by the casting industry. In this work, mechanical mold vibration is applied to an Al-Si eutectic (Al-12.5% Si) alloy at a frequency of 100 Hz and variable amplitudes in the range of 18-199 m. It is shown that the silicon morphology was strongly influenced by the level of vibration amplitude. Generally, increasing the vibration amplitude tends to reduce the lamellar spacing and change the silicon morphology to become more fibrous. However, exceeding a critical value of vibration amplitude tends to coarsen the silicon. The corresponding changes in mechanical properties are also investigated. It is shown that the maximum elongation is more influenced by vibration than the tensile strength for the range of conditions tested here.
Measured temperature and composition profiles are reported for a number of flames. Implications c... more Measured temperature and composition profiles are reported for a number of flames. Implications concerning flame structure are deduced, with emphasis on soot formation and on correlation involving conserved scalars.
We previously showed that infrared thermography (IRT) could be used to quantify viable Escherichi... more We previously showed that infrared thermography (IRT) could be used to quantify viable Escherichia coli, a representative gram-negative bacterium, in liquid growth media. Here, we evaluated the ability of IRT to enumerate a viable representative gram-positive organism, Staphylococcus aureus. We found that the energy content (EC) of the media was strongly positively correlated (r = 0.999) to measured viable counts of S. aureus ranging from 85 colony-forming units (CFU)/ml to $4 Â 10 8 CFU/ml. The EC of S. aureus was $2-fold higher than that of E. coli at comparable cell concentrations suggesting that IRT may be used to distinguish genera.
Quantifying viable bacteria in liquids is important in environmental, food processing, manufactur... more Quantifying viable bacteria in liquids is important in environmental, food processing, manufacturing, and medical applications. Since vegetative bacteria generate heat as a result of biochemical reactions associated with cellular functions, thermal sensing techniques, including infrared thermography (IRT), have been used to detect viable cells in biologic samples. We developed a novel method that extends the dynamic range and improves the sensitivity of bacterial quantification by IRT. The approach uses IRT video, thermodynamics laws, and heat transfer mechanisms to directly measure, in real-time, the amount of energy lost as heat from the surface of a liquid sample containing bacteria when the specimen cools to a lower temperature over 2 min. We show that the Energy Content (EC) of liquid media containing as few as 120 colony-forming units (CFU) of Escherichia coli per ml was significantly higher than that of sterile media (P < 0.0001), and that EC and viable counts were strongly positively correlated (r = 0.986) over a range of 120 to approximately 5 Â 10 8 CFU/ml. Our IRT approach is a unique non-contact method that provides real-time bacterial enumeration over a wide dynamic range without the need for sample concentration, modification, or destruction. The approach could be adapted to quantify other living cells in a liquid milieu and has the potential for automation and high throughput.
The effects of magnetic field on the microgravity combustion characteristics of a single methanol... more The effects of magnetic field on the microgravity combustion characteristics of a single methanol droplet in homogeneous flow are numerically investigated to develop an effective magnetic control method for microgravity droplet combustion and spray combustion systems. First, governing equations of microgravity single methanol droplet combustion under a homogeneous magnetic field based on an unsteady two-dimensional, spherically symmetric model including single-step chemistry are presented. Employing numerical modeling, several combustion behaviors are calculated taking into account the effect of the unsteady magnetic field profiles at the flame front. It is found that the flame front becomes deformed and is elongated in the direction of the magnetic field due to the inhomogeneous magnetic pressure distribution at the interface between the fuel vapor phase and the oxidizer phase. This nonuniformity of magnetic pressure is caused by the transient deformation of the magnetic field with refraction of magnetic flux at the flame front due to the difference of magnetic susceptibility between the diamagnetic fuel vapor phase and the paramagnetic oxidizer phase.
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Papers by Kozo Saito