Kenji Imou

Methanol or ethanol produced from woody biomass: which is more advantageous?

In this study, two conversion technologies--methanol synthesis and ethanol fermentation--were compared and CO(2) mitigation effect was estimated. The biomethanol production process was revealed as being preferable to the bioethanol process in terms of thermal efficiency, carbon conversion and environmental burden except electrical energy consumption. When biofuels are employed in internal combustion engines, biomethanol has greater potential for gasoline substitution, but the difference in expected CO(2) reduction is rather small due to higher power consumption in methanol production. Consequently, from a short-term perspective, bioethanol is preferable since it can readily substitute the gasoline for conventional vehicles. From a long-term perspective, however, biomethanol has greater potential for gasoline substitution and CO(2) mitigation.

Effect of thermal pretreatments on hydrocarbon recovery from Botryococcus braunii.

Thermal pretreatment were tested to increase the recovery of hydrocarbons from Botryococcus braunii/water mixtures via extraction with hexane. The effectiveness of treatment temperature was dependent on the B. braunii strain and the lowest temperatures which recovered over 90% of hydrocarbons were 60, 85 and 75°C for the Yamanaka, Showa and Kawaguchi-1 strains respectively. The holding times of thermal pretreatment had less of an influence on hydrocarbon recovery than treatment temperature and, depending on the strain, recoveries of between 74.9% and 94.9% were achieved after thermal pretreatments at 80-90°C for only 2.5min. These results suggest thermal pretreatment could reduce the energy consumption of oil recovery process from wet B. braunii cells.

Seawater-Cultured Botryococcus braunii for Efficient Hydrocarbon Extraction

As a potential source of biofuel, the green colonial microalga Botryococcus braunii produces large amounts of hydrocarbons that are accumulated in the extracellular matrix. Generally, pretreatment such as drying or heating of wet algae is needed for sufficient recoveries of hydrocarbons from B. braunii using organic solvents. In this study, the Showa strain of B. braunii was cultured in media derived from the modified Chu13 medium by supplying artificial seawater, natural seawater, or NaCl. After a certain period of culture in the media with an osmotic pressure corresponding to 1/4-seawater, hydrocarbon recovery rates exceeding 90% were obtained by simply mixing intact wet algae with n-hexane without any pretreatments and the results using the present culture conditions indicate the potential for hydrocarbon milking. Highlights Seawater was used for efficient hydrocarbon extraction from Botryococcus braunii. The alga was cultured in media prepared with seawater or NaCl. Hydrocarbon recovery rate exceeding 90% was obtained without any pretreatment.

Automatic diagnosis of plant disease - Spectral reflectance of healthy and diseased leaves

Abstract Accurate diagnosis of plant diseases is needed to minimize the use of agricultural chemicals. Because it must be designed for laborsaving and work efficiency in the actual management system, this automation is a critical problem for the future. The final objective of this project is the construction of an automated system to diagnose plant disease. This article reports on the spectral reflectance characteristics of healthy and diseased leaves. The results obtained were as follows: 1. A wavelength that distinguishes between two categories of leaves (healthy and diseased) was identified using the Distinction Index (D.I.). 2. The difference between near ultraviolet information and near infra-red information gave the largest D.I., and the ratio of red wavelength centered at 660 nm to violet wavelength centered at 400 nm gave the largest D.I. in the visible range.

Isolation and characterization of two squalene epoxidase genes from Botryococcus braunii, race B.

The B race of the green microalga Botryococcus braunii produces triterpene hydrocarbons, botryococcenes and methylsqualenes that can be processed into jet fuels with high heating values. In this alga, squalene is also converted into membrane sterols after 2,3-epoxidation. In the present study, cDNA clones of two distinct squalene epoxidases (BbSQE-I and -II) were isolated. Predicted amino acid sequences encoded on these genes are 45% identical with each other. Introduction of BbSQE-I or -II into Saccharomyces cerevisie erg1 mutants resulted in the complementation of ergosterol auxotrophy. The relative expression level of SQE-II increased 3.5-fold from the early stage to the middle phase of a culture period of 42 days, while that of SQE-I was almost constant throughout the culture period. Southern blot analyses suggested that these genes are single-copied genes. This is the first report on the isolation of functional SQEs that are encoded in duplicated loci in the algal genome.

Culture of the green microalga Botryococcus braunii Showa with LED irradiation eliminating violet light enhances hydrocarbon production and recovery.

The green microalga Botryococcus braunii (B. braunii), race B, was cultured under light-emitting diode (LED) irradiation with and without violet light. This study examined the effect of violet light on hydrocarbon recovery and production in B. braunii. C34 botryococcene hydrocarbons were efficiently extracted by thermal pretreatments at lower temperatures when the alga was cultured without violet light. The hydrocarbon content was also higher (approximately 3%) in samples cultured without violet light. To elucidate the mechanism of effective hydrocarbon recovery and production, we examined structural components of the extracellular matrix (ECM). The amounts of extracellular carotenoids and water-soluble polymers extracted by thermal pretreatment from the ECM were decreased when the alga was cultured without violet light. These results indicate that LED irradiation without violet light is more effective for hydrocarbon recovery and production in B. braunii. Furthermore, structural ECM components are closely involved in hydrocarbon recovery and production in B. braunii. Graphical Abstract Hydrocarbons were more readily extracted with organic solvents from Botryococcus braunii after thermal pretreatments when the alga was cultured LED illuminations without violet light.

Landmark direction angle estimation based on omnidirectional image

In order to estimate landmark direction angle to localize robot in an artificial environment based on omnidirectional image, this paper introduces the method about low pass filter noise elimination, artificial landmark features detection and landmark direction angle estimation algorithms. Landmark feature detection proposed that red landmark pixels beyond the threshold were extracted as a small area and the center of gravity was calculated for the extracted small area representing the candidate of one landmark. The blue patch provides as compensation to further distinguish the landmark from other objects in a complex environment. Two type experiments were done. The landmark detection experiment proved that the low-pass filter noise elimination was effective. Another experiment was conducted on the level cement ground in a 5×5-m area in the sunlight. 16 test positions were chose to test. Results showed that the MAE and RMSE of landmark direction angles were 1.12 degree and 1.30 degree, respectively. The proposed direction angle estimation method is high accuracy, low time-consuming computation and good robustness.

3D Positioning for Mobile Robot Using Omnidirectional Vision

This paper introduces a local 3D positioning system using omnidirectional vision for mobile robot navigation in a known indoor/outdoor working field environment. The omnidirectional vision image can provide 360 degree information around the sensor and the direction angle information data with the principle point of camera obtained relatively accurate from the image. The approached system set four red artificial landmarks as a rectangle on the corners of an operating spot. The x and y horizontal location was calculated based on the direction angles of landmarks. The z axis value was calculated via using the relation between sensor height and distance from senor to landmark. Position experiment was conducted on the field in a 5 m×5 m rectangular area and straight-line driving practical experiments was conducted on a 30 m distance field road. Sixteen test positions were chose on average. Results showed that the distance RMS error between estimated position and test position was about 6.84 cm and maximum error was about 12 cm. The practical experimental results showed that the distance RMS error was about 7.34 cm. In conclusion, the novel positioning system is feasible and the accuracy is good.

Localization System Based on Artificial Landmark and Omnidirectional Vision

We propose a localization system based on artificial landmarks and omnidirectional vision for agricultural vehicle navigation. The system sets four red artificial landmarks as a rectangle in the corners of an operating spot and estimates an absolute position. This paper introduces an algorithm in which red landmark pixels beyond the threshold were extracted as a small area and the center of gravity was calculated for the extracted small area representing the position of one landmark in order to obtain the positions of four representative landmarks and then estimate the four directional angles of the landmarks using only one omnidirectional image. Camera location was estimated using the center of gravity of the four intersections formed by four arcs according to geometric transformation based on the four directional angles of the landmarks. The experiments were conducted under natural sunlight in a 50×50-m square area to verify the system. Experimental results showed that the maximum and mean position errors were about 46.96 and 31.99 cm, respectively; camera tilt experiments showed that the tilt angle had some effect on errors, but not to an obvious level, and it was not necessary to compensate for the errors caused by camera tilt. In conclusion, this system is an effective selection for agricultural vehicle navigation in future.

Identification of plants for wild flower garden

Abstract The use of wildflowers has become popular for creating aesthetic public landscaping. As weeding costs are rather expensive, automation of weeding would help reduce maintenance costs. In this study, as a step towards automation of weeding, identification of plants for wildflower gardens was performed by image processing. Shape feature analysis was applied to the binary images to identify the plant as one of four species (aster, pansy, treasure flower, and California Poppy). As features, roundness, first invariant central moment, area, and perimeter were studied for each plant type. Mahalanobis’ generalized distance was used in identification of the plants. The results showed that the best shape features for identifying these plants were roundness and first invariant central moment.