Size reduction by interpolation in fuzzy rule bases

Fuzzy control is at present still the most important area of real applications for fuzzy theory. It is a generalized form of expert control using fuzzy sets in the definition of vague/linguistic predicates, modeling a system by If...then rules. In the classical approaches it is necessary that observations on the actual state of the system partly match (fire) one or several rules in the model (fired rules), and the conclusion is calculated by the evaluation of the degrees of matching and the fired rules. Interpolation helps reduce the complexity as it allows rule bases with gaps. Various interpolation approaches are shown. It is proposed that dense rule bases should be reduced so that only the minimal necessary number of rules remain still containing the essential information in the original base, and all other rules are replaced by the interpolation algorithm that however can recover them with a certain accuracy prescribed before reduction. The interpolation method used for demonstration is the Lagrange method supplying the best fitting minimal degree polynomial. The paper concentrates on the reduction technique that is rather independent from the style of the interpolation model, but cannot be given in the form of a tractable algorithm. An example is shown to illustrate possible results and difficulties with the method.     

Formation and Characterization of Ce3ZrO8 Prepared by the Hydrazine Method

A compound denoted as (Ce_0.75Zr_0.25)O₂ (Ce, ZrO₈) is formed near room temperature from cerium and zirconium nitrates using hydrazine monohydrate. It has a cubic unit cell with a = 0.5342 nm. Characterization of powders heated to various temperatures at 10°C/min demonstrates that the specific surface area does not decrease below 20 mVg until >1000°C.     

Optimal production-inventory policy for make-to-order versus make-to-stock based on the M/Er/1 queuing model

This paper analyzes a multi-product production / inventory system where demands for each item arrive according to a Poisson process and the production time for each product has an Erlang distribution. The paper proposes an optimality condition that specifies whether each product should be produced make-to-stock or make-to-order. In the event a product should be produced make-to-stock, an approach for computing the optimal base-stock level is proposed. Numerical examples are given for illustrative purpose.     

Clinical study of total intravenous anesthesia with droperidol, fentanyl and ketamine--effects of nicardipine, diltiazem and nifedipine on intraoperative hypertension

The purpose of the study was to explore the relationship between the exposure of adolescents in the seventh and eighth grades to cigarette advertising and their being smokers. A survey questionnaire given to 602 adolescents assessed their exposure to cigarette advertising and provided measures of their smoking behavior, demographic characteristics, and some psychosocial variables. The results indicated that exposure to cigarette advertising and having friends who smoked were predictive of current smoking status. Adolescents with high exposure to cigarette advertising were significantly more likely to be smokers, according to several measures of smoking behavior, than were those with low exposure to cigarette advertising. The findings extend previous research identifying factors that may play a role in the initiation and maintenance of smoking among adolescents.     

Formation, Characterization, and Hot Isostatic Pressing of Cr2O3-Doped ZrO2 (0,3 mol% Y2O3) Prepared by Hydrazine Method

In the ZrO₂-Cr₂O₃ system, metastable t -ZrO₂ solid solutions containing up to 11 mol% Cr₂O₃ crystallize at low temperatures from amorphous materials prepared by the hydrazine method. The lattice parameter c decreases linearly from 0.5149 to 0.5077 nm with increased Cr₂O₃ content, whereas the lattice parameter a is a constant value ( a = 0.5077 nm) regardless of the starting composition. At higher temperatures, transformation (decomposition) of the solid solutions proceeds in the following way: t (ss)→ t (ss) + m + Cr₂O₃→ m + Cr₂O₃. Above 11 mol% Cr₂O₃ addition, c-ZrO₂ phases are formed in the presence of Cr₂O₃. The t -ZrO₂ solid solution powders have been characterized for particle size, shape, and surface area. They consist of very fine particles (15–30 nm) showing thin platelike morphology. Dense ZrO₂(3Y)-Cr₂O₃ composite ceramics (∼99.7% of theoretical) with an average grain size of 0.3 μm have been fabricated by hot isostatic pressing for 2 h at 1400°C and 196 MPa. Their fracture toughness increases with increased Cr₂O₃ content. The highest K _Ic value of 9.5 MPa·;m^1/2 is achieved in the composite ceramics containing 10 mol% Cr₂O₃.     

Hot isostatic pressing of tetragonal ZrO2 solid-solution powders prepared from acetylacetonates in the system ZrO2-Y2O3-Al2O3

In compositions having ZrO₂/Y₂O₃=(74.25–71.25)/(0.75–3.75) (mol% ratio) with 25 mol% Al₂O₃, metastable t-ZrO₂ solid solutions crystallize at 780° to 860°C from amorphous materials prepared by the simultaneous hydrolysis of zirconium, yttrium and aluminium acetylacetonates. Hot isostatic pressing has been performed for 1 h at 1130 and 1230°C under 196 MPa using their powders. Two kinds of material are fabricated: (i) perfect ZrO₂ solid-solution ceramics and (ii) composites of ZrO₂ solid solution and -Al₂O₃. Their mechanical properties are examined, in connection with microstructures and t/m ZrO₂ ratios. Composites with a homogeneous dispersed -Al₂O₃ derived from solid-solution ceramics result in a remarkable increase of strength.