Abstract

This paper presents the effect of corrugation geometry on the crushing behavior, energy absorption, failure mechanism, and failure mode of woven roving glass fibre/epoxy laminated composite tube. Experimental investigations were carried out on three geometrical different types of composite tubes subjected to axial and lateral compressive loadings. On the addition to a radial corrugated composite tube, cylindrical composite tube, and corrugated surrounded by cylindrical tube were fabricated and tested under the same condition in order to know the effect of corrugation geometry. The results showed that the loading carrying capability is significantly influenced by corrugation geometry in axial crushing. However, no affect of corrugation geometry was observed for lateral crushing. Load–displacement curve was plotted for all conducted tests, thus clear comparison between different specimen's geometry was achieved. It is also found that radial corrugation could significantly applicable as a stable and effective energy absorber.

Abstract

A numerical simulation of a two-stage reciprocating compressor has replicated the operations of the compressor under various conditions for the development of diagnostic features for predictive condition monitoring. The simulation involves the development of a mathematical model of five different physical processes: speed–torque characteristics of an induction motor, cylinder pressure variation, crankshaft rotational motion, flow characteristics through valves and vibration of the valve plates. Modelling both valve leakage and valve spring deterioration has also been achieved. The simulation was implemented in a MATLAB environment for an efficient numerical solution and ease of result presentation. For normal operating conditions, the simulated results are in good agreement with the test results for cylinder pressure waveforms and crankshaft instantaneous angular speed (IAS). It has been found that both the IAS fluctuation and pressure waveform are sensitive detection features for compressor faults such as valve leakage and valve spring deterioration. However, IAS is preferred because of its non-intrusive measurement nature. Further studies using the model and experiments are being undertaken in order to develop fault detection features for compressor driving motors and transmission systems.

Abstract

This paper is devoted to study the effect of corrugation geometry on the crushing behavior, energy absorption, failure mechanism, and failure mode of woven roving glass fibre/epoxy laminated composite tubes. A comprehensive experimental program has been carried out on two geometrically different types of composite tubes subjected to axial compressive loading conditions. A cylindrical composite tube has been fabricated and tested in order to provide a means of comparison with corrugated composite tube. Both are tested under the same condition to establish the effect of corrugation geometry. The results showed that the initial failure was dominated by interfacial failure, while a folded zone grows progressively down in a form of mushrooming failure. The results also showed that radial corrugated composite tube (RCCT) exhibited good energy absorption capability than circular composite tube (CCT).

Abstract

The turbine of an automotive turbocharger is essentially one acoustic element in the exhaust system which lies between the primary noise source, the gas pulsations through the exhaust valves, and the primary noise radiation element, the exhaust tailpipe orifice. As such, like every other acoustic element of the exhaust system, it has a passive effect on the propagation of the primary exhaust noise. Thus if a comprehensive model of the acoustic propagation through the entire exhaust system of a turbocharged engine is sought, an acoustic model of the turbine is a prerequisite.

This paper presents a preliminary attempt to create such a model. The model is a purely fluid mechanic one, without recourse to any empiricism such as a turbine map. The nonlinear equations of the fluid flow are developed and solved for steady flow, to determine the mean convective flow effects upon the noise. The full time-domain equations are then linearised and solved for a single frequency of sound.

Results are given from both the steady flow and the acoustic analyses. The latter are presented in terms of both transmission loss and four-pole parameters. The model is found to give a rational representation of the passive effect of a turbine rotor.

Abstract

This paper presents a one-dimensional acoustic model for prediction of the frequencies of

self-excited oscillation and acoustic mode shapes in combustion systems. The impedance of

the combustion system is represented in terms of a frequency response function (FRF).

Impedances of the settling and combustion chambers are predicted by using the acoustic

model, taking into account the temperature distribution in the combustion chamber. Reasonably

good agreement between measured and predicted acoustic resonance frequencies and

mode shapes was achieved. Some data on stability regimes are discussed.

# 2003 Elsevier Science Ltd. All rights reserved.

Keywords: Combustion; Instability; Eigen-frequencies; Prediction; Measurement

Abstract

Experimental investigations have been carried out to measure axial effective thermal conductivities of

packed beds for a number of particles and catalyst pellets. Measurements were made for three gases (air,

nitrogen and carbon dioxide) in beds packed with ball bearings, copper chromite, chromia alumina, alumina

hollow cylinders and alumina spheres. A glass vacuum vessel was employed for most measurements,

but a thin wall stainless steel vessel was used in a few experiments.

Empirical correlations to predict the axial effective thermal conductivity of packed bed reactors have

been derived from the experimental results.

2002 Elsevier Science Ltd. All rights reserved.

Keywords: Axial thermal conductivities; Packed beds

This paper presents empirical methods for enhancing the accuracy of inductive learning systems. It

addresses the problems of: learning propositional production rules in multi-class classification tasks in

noisy domains, maintaining continuous learning when confronted with new situations after the learning

phase is completed, and classifying an object when no rule is satisfied for it.

It is shown that interleaving the learning and performance-evaluation processes, allows accurate

classifications to be made on real-world data sets. The paper presents the system ARIS which

implements this approach, and it is shown that the resulting classifications are often more accurate than

those made by the non-refined knowledge bases.

The core design decision that lies behind ARIS is that it employs an ordering of the rules according to

their weight. A rule’s weight is learned by using Bayes’ theorem to calculate weights for the rule’s

conditions and to combine them. This model focuses the analysis of the knowledge base and assists the

refinement process significantly.

The system is non-interactive, it relies on heuristics to focus the refinement on those experiments that

appear to be most consistent with the refinement data set. The design framework of ARIS consists of a

tabular model for expressing rule weights, and the relationship between refinement cases and the rules

satisfied for each case to focus the refinement process. The system has been used to refine knowledge

bases created by ARIS itself, as well as to refine knowledge bases created by the RIPPER and C4.5

systems [6,25] in ten selected domains. Two main advantages have been observed. First, the ability to

gradually improve the knowledge base as the refinement proceeds. Second, is the ability to learn strong

rules utilising condition’s weight using minimum covering algorithm. Thus, by taking account of this

information we improve the applicability and quality of refinement