A review of expert systems for chromatography

Expert systems for chromatography are reviewed. A taxonomy is proposed that allows present (and future) expert systems in this area to be classified and facilitates an understanding of their inter-relationship. All the systems are described focusing on the reasons for their development, what their purpose was and how they were to be used. The engineering methods, knowledge representations, tools and architectures used for the systems are compared and contrasted in a discussion covering all the stages of the development life cycle of expert systems. The review reveals that too often developers of expert systems for chromatography do not justify their decisions on engineering matters and that the literature suggests that many ideas advocated by knowledge engineers are not being used

Towards an expert system for enantioseparations: induction of rules using machine learning

A commercially available machine induction tool was used in an attempt to automate the acquisition of the knowledge needed for an expert system for enantioseparations by High Performance Liquid Chromatography using Pirkle-type chiral stationary phases (CSPs). Various rule-sets were induced that recommended particular CSP chiral selectors based on the structural features of an enantiomer pair. The results suggest that the accuracy of the optimal rule-set is 63% + or - 3% which is more than ten times greater than the accuracy that would have resulted from a random choice

The Hercules-Lyra Association revisited New age estimation and multiplicity study

The Her-Lyr assoc., a nearby young MG, contains a few tens of ZAMS stars of SpT F to M. The existence and the properties of the Her-Lyr assoc. are controversial and discussed in the literature. The present work reassesses properties and the member list of Her-Lyr assoc., based on kinematics and age. Many objects form multiple systems or have low-mass companions and so we need to account for multiplicity. We use our own new imaging obs. and archival data to identify multiple systems. The colors and magnitudes of kinematic candidates are compared to isochrones. We derive further information on the age based on Li depletion, rotation, and coronal and chromospheric activity. A set of canonical members is identified to infer mean properties. Membership criteria are derived from the mean properties and used to discard non-members. The candidates selected from the literature belong to 35 stellar systems, 42.9% of which are multiple. Four multiple systems are confirmed in this work by common proper motion. An orbital solution is presented for the binary system HH Leo B and C. Indeed, a group of candidates displays signatures of youth. 7 canonical members are identified. The distribution of EWLi of canonical Her-Lyr members is spread widely and is similar to that of the Pleiades and the UMa group. Gyrochronology gives an age of 257+-46 Myr which is in between the ages of the Pleiades and the Ursa Major group. The measures of chromospheric and coronal activity support the young age. Four membership criteria are presented based on kinematics, EWLi, chromospheric activity, and gyro. age. In total, 11 stars are identified as certain members including co-moving objects plus additional 23 possible members while 14 candidates are doubtful or can be rejected. A comparison to the mass function, however, indicates the presence of a large number of additional unidentified low-mass members.Comment: 19 pages 16 figure

Minimal length scales for the existence of local temperature

We review a recent approach to determine the minimal spatial length scales on which local temperature exists. After mentioning an experiment where such considerations are of relevance, we first discuss the precise definition of the existence of local temperature and its physical relevance. The approach to calculate the length scales in question considers homogenous chains of particles with nearest neighbor interactions. The entire chain is assumed to be in a thermal equilibrium state and it is analyzed when such an equilibrium state at the same time exists for a local part of it. The result yields estimates for real materials, the liability of which is discussed in the sequel. We finally consider a possibility to detect the existence or non-existence of a local thermal state in experiment.Comment: review, 13 pages, 11 figure