Fuzzy logic based on-line efficiency optimization control of anindirect vector-controlled induction motor drive

Improvement of adjustable speed drive system efficiency is important not only from the viewpoints of energy saving and cooling system operation, but also from the broad perspective of environmental pollution. The paper describes a fuzzy logic based on-line efficiency optimization control of a drive that uses an indirect vector controlled induction motor speed control system in the inner loop. At steady-state light-load condition, a fuzzy controller adaptively decrements the excitation current on the basis of measured input power such that, for a given load torque and speed, the drive settles down to the minimum input power, i.e., operates at maximum efficiency. The low-frequency pulsating torque due to decrementation of rotor flux is compensated in a feedforward manner. If the load torque or speed command changes, the efficiency search algorithm is abandoned and the rated flux is established to get the best transient response. The drive system with the proposed efficiency optimization controller has been simulated with lossy models of the converter and machine, and its performance has been thoroughly investigated. An experimental drive system with the proposed controller implemented on a TMS320C25 digital signal processor, has been tested in the laboratory to validate the theoretical development     

Appropriation of space in a design office

Data from an exploratory study of space usage in a design office are reported and discussed. The argument comprises a critique of functionalist, technically utilitarian, design theory: a theory in which different groups of building users tend to be regarded as homogeneous entities. A quantitative and a qualitative analysis of the data are presented. These point to the presence among users of divergent definitions, views, of the appropriate functional bases for office layout — a factor not adequately accounted for in orthodox functional theory. In interpreting this information, reference is made to the social relations, specifically the power relations, of the groups of office personnel who express them.     

COMPOSITION OF THE BASIC NITROGEN COMPOUNDS OF DISTILLATE COAL LIQUIDS

The basic nitrogen compounds in the 300-600°F boiling range are predominately pyridines and quinolines for thermal liquefaction processes and are anilines for catalytic processing. The compounds are more numerous in the catalytic materials so that the specific compound identification has been made for only about 50% of the total basic nitrogen compound fraction whereas 75 to 85% of the individual compounds could be identified from samples generated by thermal processing. In comparing the amounts of compound classes from thermal or catalytic processing, it is concluded that nitrogen ring heterocycles (pyridines or quinolines) are primary products from coal dissolution and, by inference, these compound classes contain the basic nitrogen that is present in coals in the Illinois basin.     

NMR study of galactomannans from the seeds of mesquite tree (Prosopis juliflora (Sw) DC)

The seed gum from Prosopis juliflora is a galactomannan polysaccharide, which is located in the endosperm. Regarding P. juliflora galactomannan structural studies, there are reports on galactose substitutional pattern, but supporting data by NMR correlation studies are scarce. In this work, a procedure to obtain P. juliflora gum without contamination was employed and the gum was studied by NMR spectroscopy. Overall, results show that mesquite seed has a 1.1:1 Man/Gal ratio.     

Dose-effect study on the antioxidant properties of leaves and outer bracts of extracts obtained from Violetto di Toscana artichoke

Artichoke (Cynara scolymus L.) is an edible vegetable largely used in the Mediterranean diet and in folk medicine. The present paper discusses the analysis of the polyphenol content of leaves and outer bracts of Violetto di Toscana artichoke using different extraction procedures with the aim of establishing a correlation between polyphenol subclasses and antioxidant activity measured on human LDL oxidized by copper ions. HPLC/DAD and HPLC/MS analyses revealed that both the matrixes contain identical polyphenol subclasses, with mainly quantitative differences. The antioxidant effect of four artichoke extracts decreases in the following order when the sum of total phenolic compounds was considered: ethanolic extract from leaves (IC₅₀ = 2.92 ± 0.46 μM); ethanolic extract from outer bracts (IC₅₀ = 4.04 ± 0.21 μM); ethyl acetate extract from leaves (IC₅₀ = 4.91 ± 0.11 μM); ethyl acetate extract from outer bracts (IC₅₀ = 10.18 ± 1.6 μM). IC₅₀ were also calculated considering the concentrations of single polyphenol subclasses. In both cases, the potency of antioxidant properties was not related to the amount of total polyphenols or the single subclasses.     

Clustering factor estimation for totally clustered attributes

Cost models based on the clustering factor (CF) of the attributes have been proposed and shown to be attractive for block access estimation in databases, thanks to their accuracy and economy of use. While query optimizers can use the actual CFs, measured from the data, physical design methods and tools must rely on estimates before the data are stored.

In this paper we present a CF estimation procedure which can be applied to totally clustered attributes (e.g. ordered attributes). Simple and accurate approximations of the derived formulas are also introduced.

Simulations show the accuracy of the proposed CF estimates and the improvment in their behaviour compared to previously published estimates. Reliability for physical design of cost models based on the CF in the presence of a skewed data distribution is also discussed.