FUNCTION-BASED CANDIDATE DISCRIMINATION DURING MODEL-BASED DIAGNOSIS

We propose function for candidate discrimination, i.e., suspect ordering during model-based diagnosis. Function offers advantages over structure and fault probabilities currently being used for candidate discrimination. It is readily available from device design, unlike fault probabilities, which are hard to obtain. Function-based discrimination is not dependent on the topology of the device, unlike structure-based discrimination. We propose classes as a scheme for representation of function. As part of classes, we define a set of function primitives and provide a framework for identifying the functions of components and subsystems of a device. The representation scheme is domain independent. We propose a function-based technique for candidate discrimination called the default order technique, and outline a diagnosis algorithm that applies the technique to the class model of a device. Function-based diagnosis is in addition to and as a supplement for model-based diagnosis based on behavior and structure. We demonstrate by qualitative analysis that function-based discrimination is at least as effective as fault probabilities for candidate discrimination of simple devices. In complex devices, function facilitates explanation generation based on causality, which is a desirable feature of diagnosis systems. Our discrimination technique provides a functional basis for partitioning components in the practicable version of the minimum entropy technique proposed by deKleer.     

Continued fraction expansion and inversion by ‘rearranged’ Routh tables

The Routh algorithm is known to be the simplest method for continued fraction expansion and inversion but it faces a serious limitation when the first column entry of any row of the Routh table becomes zero (but not a zero row). In this paper a remedy for such situations is proposed by rearranging the coefficients of the row in which zero entry has occurred in the first column of the Routh table. All possible cases, where the first column entry of the Routh table may become zero, are discussed for Cauer's first and second forms and are illustrated by numerical examples. The coefficients of the rearranged Routh table are also calculated by the usual Routh algorithm, hence it is equally suitable for digital computation.     

Synthesis of sub-optimal feedback controls for a class of distributed parameter systems†

Technique are derived for the synthesis of sub-optimal feedback controls for parabolic and first-order hyperbolic systems. An explicit result for the time-invariant gain of a specified controller is obtained by a least square approximation of the closed-loop control to the optimal open-loop control. If a least square approximation of the state trajectories is used, a parameter search is shown to give the time-invariant gain. A time-varying gain can be obtained by a re-definition of the original optimal control problem, again with the controller functionality specified. The only require-mont in the closed-loop synthesis is that an optimal open-loop solution exists and is computable.     

Recursive least-squares parameter estimation in SISO systems via Poisson moment functionals Part 1. Open–loop systems

A recursive least-squares parameter estimation algorithm based on the Poisson moment functional (PMF) approach for S1SO systems in open-loop is presented in this paper. The proposed algorithm is suitable for on-line parameter estimation of real-world problems. Normalized PMFs are used to improve the performance of the algorithm in noisy conditions.     

Inverse control for nonlinear excitation and governor control

This paper presents the results of a study of the Inverse Control technique for the design of excitation and governor controllers for a power system. Control laws for rotor angle and field flux are derived. The closed loop system is shown to be asymptotically stable. The system can be transferred to a new operating condition corresponding to any desired terminal voltage Vl and tie-line power P_tie. Although this control law was not experimentally tested on a power system, implementation issues are discussed in robotic and aerospace applications.     

Dielectric and Ferroelectric Properties of Ceramics in the Pb(Zn 1/3Nb2/3)O3-BaTiO3-PbTiO3 System

The use of Pb(Zn_1/3Nb_2/3)O₃ ceramics is restricted by the formation of a pyrochlore phase detrimental to both dielectric and piezoelectric properties. Recently it has been shown that a 6 mol% addition of BaTiO₃ to PZN suppresses the formation of pyrochlore phase. Phase relations and dielectric properties of ceramics in the PZN-BT-PT system are reported here. Compositions with the perovskite structure, having high dielectric constant and low temperature coefficient of capacitance, have been identified.     

Deductive efficiency,belief revision and acting

Abstract

The SNePS inference engine is optimized for deductive efficiency, i.e. all beliefs acquired via inference are added to the agent's beliefs so that future queries may be answered by a retrieval rather than rederivation. An assumption-based truth maintenance system keeps track of the derivation histories of derived beliefs. We show how such an architecture simplifies the ontology of prepositional representations of plans; acts; preconditions, and effects of actions. In addition, the deductive efficiency of the basic system automatically extends itself to efficient search of plans, and hierarchical plan decompositions.     

The development of burfi sweetened with aspartame

Sucrose was successfully replaced with the sweetener aspartame for the preparation of the indigenous dairy product burfi . Analytical conditions were standardised for the solid phase extraction of aspartame and its degradation products from burfi followed by their reverse phase HPLC. Recovery using this method was 90–97%. Aspartame at a level of 0.065% of milk w/w scored highest in terms of sweetness perception and resembled control burfi in sweetness. Storage studies at 6–8°C revealed that aspartame-sweetened burfi resembled the control burfi in retaining the sensory profile, but showed an increase in acidity and microbial load and could not retain the texture. High-performance liquid chromatography analysis revealed no degradation of aspartame in burfi , establishing its stability and hence its sweetness on storage.     

OPTIMIZATION OF KREIS TEST FOR EDIBLE OILS

Quality evaluation of edible oils is tested by different methods. Among the chemical methods, Kreis test is a promising one for early detection of rancidity, particularly aldehydes with a characteristic odor impact. Positive relationship of these breakdown products with perceived deterioration in quality evoked interest in re-examining the Kreis test. The color development in the test is critical and requires optimization. In continuation of studies in edible oils, the present investigation deals with sunflower and mustard oils. Through central composite rotatable design, response surface was fit as a function of oil quantity (0.3–3.3 mL) 1% phloroglucinol (0.08 mol) in acetic acid (0.3–3.3 mL) and incubation period (10–90 min). The polynomial fits were excellent with multiple correlation of >0.90. Optimized conditions were obtained for the two oils. Thus, use of 1 mL oil, 1 mL of 1% phloroglucinol, incubation time of 20 min and absorbance readings at 545 nm is derived and found applicable to all edible oils for routine tests.     

Raman spectra of Bi–Sr–Ca–Cu–O high temperature superconductors

Two high-temperature superconducting BiSrCaCuO compounds were fabricated as Bi_2.1Sr₄Ca₄Cu₃O_10+δ and Bi₂Sr₂Ca₂Cu₃O_10+δ. The X-ray diffraction patterns of both the compounds show that Bi_2.1Sr₄Ca₄Cu₃O_10+δ contains predominantly the high T_c 2223 phase, and Bi₂Sr₂Ca₂Cu₃O_10+δ the low T_c 2212 and high T_c 2223 phases, in equal amounts. The Raman spectra of these samples exhibit broad bands in the 430–512 cm^-1 region, as in the lead-substituted 2212 phase. Change in configuration due to the presence of the 2223 phase in the sample is indicated by the broadening of the 465 cm^-1 line. New bands at 611 and 678 cm^-1 are observed. Peaks in the 430–512 cm^-1 region exhibit a softening when the temperature is reduced to 93 K. This revised version was published online in November 2006 with corrections to the Cover Date.