Ozone-mist sterilisation and a web-based sensing system for greenhouse agriculture were studied. Ozone of high concentration of around 70 g/m 3 was generated by surface dielectric barrier discharges with high-frequency power. The ozone was injected into water-mist to form ozone-mist matter in a closed glass chamber. Ozone and its mist treatments were performed in a closed chamber (400 mm in height × 500 mm in dia.) which is a model of the greenhouse. The sterilisation rate of pests (aphids) was investigated using the ozone-mist as well as gaseous ozone and chemical synthetics. The ozone-mist sterilisation rate of 90-100% was attained, which is comparable to that achieved by chemicals. A web-based management system combined with the analysing technology of the digital camera images of plant state was developed to predict plant growth and pest development in the greenhouse. It is shown that three colour channels (Red, Green, Blue: RGB) and the greenindex defined by the colour channels are useful to monitor plant growth on a website. Several vegetables were planted in the greenhouse (W: 3 m ×D: 4 m × H: 2 m) and observed by taking digital camera images during 63 days. The daily data of RGB and greenindex were immediately added by sending the real-time images to the remote site through the Internet. It is shown that the greenindex (2 G-R-B) gradually decreases from 42 days to 53 days after the saturated high value during 29 days and 42 days. A web-based greenhouse management system using the digital camera images has the potential to sense plant state in a greenhouse and offers an inexpensive means for small-scale rural farms.

We developed a portable ozone-mist sterilization system to exterminate pests (harmful insects) in agricultural field and greenhouse. The system is composed of an ozone generator, an ozone-mist spray and a small container of ozone gas. The ozone generator can supply highly concentrated ozone using the surface dielectric barrier discharge. Ozone-mist is produced using a developed nozzle system. We studied the effects of ozone-mist spray sterilization on insects and agricultural plants. The sterilization conditions are estimated by monitoring the behavior of aphids and observing the damage of the plants. It was shown that aphids were exterminated in 30 s without noticeable damages of the plant leaves. The reactive radicals with strong oxidation potential such as hydroxyl radical (*OH), hydroperoxide radical (*HO2), the superoxide ion radical (*O-2(-)) and ozonide radical ion (*O-3(-)) can increase the sterilization rate for aphids.

An ozonizer operating in water for the generation of ozone water was proposed and examined. The key to ozone generation was the use of a flat circular Shirasu porous glass (SPG) with a mean pore diameter of 10�m, which functioned in bubble supply and the formation of micro-barrier discharges. The micro-barrier discharges were formed in micropores of the SPG, and bubbles formed in contact with the SPG surface facing the water phase side. The higher the applied ac voltage, the higher the uniformity of discharges and ozone concentration became. In the case of a SPG membrane with a mean pore diameter of 10�m, we confirmed that an optimal gas pressure existed at around 120kPa.

An ozonizer operating in water for the generation of ozone water was proposed and examined. The key to ozone generation was the use of a flat circular Shirasu porous glass (SPG) with a mean pore diameter of 10�m, which functioned in bubble supply and the formation of micro-barrier discharges. The micro-barrier discharges were formed in micropores of the SPG, and bubbles formed in contact with the SPG surface facing the water phase side. The higher the applied ac voltage, the higher the uniformity of discharges and ozone concentration became. In the case of a SPG membrane with a mean pore diameter of 10�m, we confirmed that an optimal gas pressure existed at around 120kPa.

An ozonizer operating in water for the generation of ozone water was proposed. The key to ozone generation was the use of a Shirasu-porous-glass (SPG), which functioned in bubble Supply and the formation of micro-barrier discharges. A mesh electrode was put on the SPG surface facing the gaseous phase side, and ac voltage was supplied to the electrode. Micro-barrier discharges were formed in micropores of the SPG, and bubbles formed in contact with the SPG surface facing the water phase side. The higher the applied ac voltage. the higher the uniformity of discharges and ozone concentration. [DOI: 10.1143/JJAP.47.8030]

Reduction and recycling of carbon dioxide (CO2) were performed using a non-thermal plasma produced by a surface discharge at atmospheric pressure. Useful hydrocarbons (CHs) such as dimethyl ether and methane were produced at the discharge voltage of 11kV, when hydrogen (H2) gas was mixed with CO2 and the mixture ratio was 50%. The conversion of CO2 to the CHs mixing with water vapor of 50% requires a higher discharge voltage of 12kV. The conversion ratios to the hydrocarbons were several percentage in both H2 mixture and water vapor mixture cases.