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Editorial - Special issue section on Brain-like Computing and Applications

Miki T., Yamakawa T.

Journal of Automation Mobile Robotics and Intelligent Systems

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2010

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Vol. 4, No. 2

23-24

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A simple local navigation system inspired by hippocampal function and its autonomous mobile robot implementation

Miki T., Hayashi H., Goto Y., Watanabe M., Inoue T.

Journal of Automation Mobile Robotics and Intelligent Systems

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2010

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Vol. 4, No. 2

31-38

EN

We propose a practical simple local navigation system inspired by the sequence learning mechanism of the entorhino-hippocampal system. The proposed system memorizes a route as sequences of landmarks in the same way humans do. The proposed local navigation system includes a local route memory unit, landmark extraction unit, and learning-type matching unit. In the local route memory unit, the concept of the sequence learning mechanism of the entorhino-hippocampal system is implemented using a fully connected network, while a sequence of landmarks is embedded in the connection matrix as the local route memory. This system has two operation modes: learning and recall modes. In learning mode, a sequence of landmarks, i.e. a local route, is represented by enhanced loop connections in the connection matrix. In recall mode, the system traces the stored route comparing current landmarks with the stored landmarks using the landmark extraction and learning-type matching units. The system uses a prospective sequence to match the current landmark sequence with the recalled one. Using a prospective sequence in the route comparison allows confirmation of the correct route and deals with any slight change in the current sequence of landmarks. A certainty index is also introduced for judging the validity of the route selection. We describe a basic update mechanism for the stored landmark sequence in the case of a small change in the local route memory. The validity of the proposed system is confirmed using an autonomous mobile robot with the proposed navigation system.

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Determination of bisphenol-A in aqueous samples by means of new multi-layer solid-phase extraction cartridges and HPLC with UV detection

Nagahashi M., Kikuchi N., Tsukahara M., Makioka S., Miki T.

Acta Chromatographica

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2001

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No. 11

75-95

EN

Research has been conducted on a new method of determining bisphenol-A, a reputed hormonal disrupter, by means of multi-layer solid-phase extraction and subsequent HPLC analysis. An isolation and concen-tration cartridge was used to isolate the analyte from aqueous samples. The bisphenol-A-containing fraction obtained from this cartridge was further purified on purification cartridge A or on purification cartridge A plus purification cartridge B. The clear bisphenol-A-containing fraction was analysed by a HPLC with UV detection; the detector was equipped with a cooling system to reduce the noise level. Conventional HPLC analysis was performed on a Zorbax ODS column. For samples containing less than a nanogram, a semi-micro ODS column was used. An Innertsil CN-3 column was also used to separate matrix compounds that interfered with the measurement of the bisphenol-A peak. By use of an internal standard satisfactory calibration curves were obtained from the two ODS columns; stability and linearity were adequate and CV values were satisfactory for amounts between 2 and 100 ng for the conventional column and between 0.2 and 40 ng for the semi-micro column. The sensitivity and reliability of the technique were tested by analysing seven river water samples and five other water samples from natural water sources. Some of these results were compared with those obtained by use of the method proposed in the Tentative Surveying Manual of Endocrine Disruptor, published by the Japanese Environmental Agency in 1998. Twenty canned non-alcoholic beverages were also analysed. Although the results obtained indicated that this analytical method was less sensitive than GC-MS, the instrumentation is approximately one-twentieth less costly. The method can be widely used for analysis of aqueous samples when there is no limitation on sample volume, for example in water analysis or in the food industry.

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Separation and estimation of bisphenol a by liquid chromatography with UV detection

Nagahashi M., Kikuchi N., Migaki E., Watanabe S., Miki T.

Acta Chromatographica

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2000

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No. 10

110-122

EN

Reliable HPLC separation and estimation of bisphenol A has been performed on a conventional ODS column with 40:60 acetonitrile–water as mobile phase and UV detection at 277 nm. Linear regression plots were obtained for the dependence of response on bisphenol A concentration in the working ranges 2 to 10 ng and 10 to 100 ng; the correlation coefficients for the plots were r = 0.9976 (n = 5) and r = 0.9987 (n = 6), respectively. Aqueous samples were applied to a solid-phase extraction cartridge packed with three layers, Bio-Rad AG 50W X8 [H+], ODS–silica, and Bio-Rad AG 1 X8 [formate–]. Eluent from this cartridge was passed through a normal-phase Florisil PR cartridge. These isolation and purification cartridges effectively separated and purified bisphenol A from spiked samples with recovery between 86 and 92%. The method was used to estimate bisphenol A in water samples.