bluuebunny/crossref_metadata_2025 huggingface dataset:
A two-degree-of-freedom ambulance stretcher suspension, Part 2: Simulation of system performance with capillary and orifice pneumatic damping
Authors: Henderson R. J. , Raine J. K.
Published: October 2002

Part 1 of this paper gave an overview of the design and dynamics of a two-degree-of-freedom pneumatic stretcher suspension. Part 2 reviews pneumatic damping methods and then investigates system isolation performance using capillary and orifice damping restrictions. These restrictors are compared by numerical simulation of the suspension response when subjected to vertical transient inputs from the ambulance floor. Very good isolation of the stretcher patient is shown to be possible when a suitable damping restriction is used. Brief observations are also made regarding expected suspension performance in pitch and the potential improvement from introducing semi-active pneumatic damping. Part 3 will report results of suspension tests on a laboratory shaking table and in an ambulance.
Design of a lightweight automotive brake disc using finite element and Taguchi techniques
Authors: Grieve D. G. , Barton D. C. , Crolla D. A. , Buckingham J. T.
Published: October 2002

Aluminium metal matrix composite brake discs offer significant weight advantages compared with the traditional cast iron rotor but have a much lower maximum operating temperature. In this study, a finite element model of an existing brake design is firstly used to predict the peak disc temperatures during two critical brake tests for both cast iron and an aluminium metal matrix composite alternative. A Taguchi analysis is then applied, enabling all the critical design and material factors of an aluminium metal matrix composite rotor to be considered collectively. Based on the results of this exercise, a parametric sensitivity study is carried out to define suitable design-material combinations for a prototype lightweight front brake disc to be used on small to medium passenger vehicles.
Stresses and deformations in overlapped diesel engine crankshafts, Part 2: Evaluation of results
Authors: Bickley I , D'Olier V , Fessler H , Hyde T. H. , Warrior N. A.
Published: October 2002

The extensive results presented in Part 1 (in the previous issue*) have been supplemented and analysed further. A large number of cross-sections which could be reasonably used to calculate nominal stresses has been listed and evaluated.

An inclined (flat, rectangular) section through the web is shown to be the best to calculate nominal stresses due to torsion, pure radial bending and bending due to crankpin forces; its width is h (see Fig. 1), the length of the shortest line joining crankpin and journal fillets in the plane of symmetry. Stress concentration factors based on these nominal stresses show only modest scatter from single curves for crankpin and journal fillets for torsion and radial bending.

Predictions using the most commonly used method underestimate shear stresses due to torsion and overestimate bending stresses.
Technical Code: Predictions of liquid fuel injector performance with gaseous fuels
Authors: Pashley N , Stone R
Published: October 2002

A method to predict the maximum flowrate of a liquid fuel injector when operating with gaseous fuels has been developed. Three injectors were tested for flow capability with four gases of various molecular masses and ratios of specific heats. Compressible flow theory has been used to nondimensionalize the results, and predictions have been made for performance with other gases and mixtures.
Design of an electrostatically excited H-type resonant gyroscope suitable for fabrication using the LIGA process
Authors: Yao L , Chowanietz E , McCormick M , Lees A
Published: October 2002

This paper presents a new design of miniaturized H-type resonant gyroscope suitable for automotive applications which is to be fabricated in electroformed metal using an emergent technology known as LIGA (the German acronym for the process steps of Lithographie, Galvanoformung and Abformung). The sensor features electrostatic drive and capacitive readout techniques. The simulation-aided design process used to obtain the final sensor structure is described in the paper. The paper also details how a set of equations for the electrostatic-structural coupled field problem is derived and implemented in conjunction with a commercial finite element analysis package. The driving and detecting circuitry are also discussed.
Combustion analysis and cycle-by-cycle variations in spark ignition engine combustion Part 1: An evaluation of combustion analysis routines by reference to model data
Authors: Ball J. K. , Raine R. R. , Stone C. R.
Published: October 2002

This paper investigates a number of new approaches to mass fraction burned analysis for application to spark ignition engine combustion processes. The rationale for these new approaches is to retain the simplicity and computational efficiency of the technique of Rassweiler and Withrow, but to overcome some of the limitations inherent in the standard methods. The approaches investigated include the use of a two-zone model to determine information about the burned and unburned gas temperatures and the modification of the standard Rassweiler and Withrow expression to incorporate polytropic indices for compression and expansion.

The investigation makes use of an engine simulation model, which was used to generate the pressure data. This technique provided a ‘known’ burn rate against which to evaluate the methods investigated. Some experimental data taken from a Rover K4 optical access engine is also presented.

The successful aspects of this investigation are the use of the Rassweiler and Withrow equation with different compression and expansion indices, and the application of this analysis to investigate crevice gas burn-up. What was found to be not successful was the use of a two-zone model for calculating gas temperatures. The results indicate that the model is, in general, not reliable for computing temperatures and this is due to the temperature gradient in the burnt zone and the disproportionately high rate of heat transfer from the mixture that burns first during combustion. The mass fraction burned calculations using this model were also found to be not as accurate as those based on simpler models.
Research on the fuzzy and dynamic monitoring of the diesel engine operating conditions
Authors: Zhang Y , Zhang Z. P. , Zhou Y. C.
Published: October 2002

In this paper the fuzzy and dynamic monitoring of mechanical equipment is studied using fuzzy techniques. Generally there are two types of condition monitoring: one is that the standard syndrome can be established in advance and, therefore, the fault samples can be identified by this; the other is that the standard syndrome is difficult to establish in advance, and information only about the operation condition of the mechanical equipment is needed. For the former the measure of fuzzy nearness can be used without using a series of weights for the characteristic parameters; for the latter the fuzzy cluster can be used without the standard syndrome. The vibration signal samples obtained from the 190A diesel engine block are identified and classified by the fuzzy measures. The results show that the fuzzy nearness and fuzzy cluster are practical and work well.
Combustion analysis and cycle-by-cycle variations in spark ignition engine combustion Part 2: A new parameter for completeness of combustion and its use in modelling cycle-by-cycle variations in combustion
Authors: Ball J. K. , Raine R. R. , Stone C. R.
Published: October 2002

This paper investigates a technique of calculating the completeness of combustion on a cycle- by-cycle basis. The technique introduces the normalized pressure rise due to the combustion parameter, ψ to describe the completeness of combustion. This parameter is based on the Rassweiler-Withrow method of calculating the mass fraction burned and is derived from the pressure-crank angle record of the engine.

Experimental data were obtained from a Rover K4 optical access engine and analysed with a combustion analysis package. A computer simulation was then used to model the data on a cycle-by-cycle basis, both with and without the completeness of combustion parameter. The paper discusses the conditions under which it is suitable to model mean engine cycles, compared with the need to model cycle-by-cycle variability, and comments on the situations in which each type of modelling would be most appropriate. The engine simulation model is also used to investigate cycle-by-cycle variability of NO emissions that have recently been obtained experimentally.

The successful aspects of this investigation are that the cycle-by-cycle variability in the completeness of combustion can be determined by use of the parameter ψ, that the inclusion of the completeness of combustion parameter improves the simulation's ability to model the experimental data both in a statistical sense (the coefficient of variation of the indicated mean effective pressure) and on a cycle-by-cycle basis and that cycle-by-cycle NO modelling results are found to compare well with experiment.
Modelling the effects of combustion and turbulence on near-wall temperature gradients in the cylinders of spark ignition engines
Authors: Jenkin R. J. , James E. H. , Malalasekera W. M.
Published: October 2002

An existing quasi-dimensional engine cycle model has been modified to enable accurate prediction of the near-wall temperature field in the burned and unburned gases. This has been achieved by dividing the cylinder into a number of discrete masses, each of which has a unique state. These discrete masses are assumed to remain stacked in layers adjacent to the cylinder walls in both the unburned gas and in the discrete segments generated during the sequential burning process. A k-ɛ turbulence model has been incorporated into the engine cycle simulation, providing information on the nature of the instantaneous in-cylinder turbulence for input to a fractal flame model to depict the flame propagation process. When this approach is applied to the prediction of the flame propagation rate, excellent comparison is afforded between simulated and measured pressure-crank angle diagrams. Further validation is provided by comparison of near-wall temperature predictions with measured ones and the essential features of the observed boundary layer behaviour are reproduced.
Weight reduction in automotive structures—an experimental study on torsional stiffness of box sections
Authors: Pine T , Lee M. M. K. , Jones T. B.
Published: October 2002

Torsional rigidity is an important performance related property of an automotive body-in-white (BIW) structure, which consists of many box hat structures or box sections. An experimental study has been carried out to determine mainly the torsional stiffness but also the elastic limit and the strength of spot-welded and adhesively bonded (and weld-bonded) box sections. The relative contribution of a variety of factors, including joining system used, steel strength, sheet thickness, section area and section design, to the properties of box sections was analysed using factorial design experimentation techniques. It was found that a significant increase in torsional stiffness could be achieved by changing the joining technique, increasing the sheet thickness, increasing the section area and, to a lesser extent, changing the section design. The results are examined and discussed in the context of weight reduction in automotive structures.
Development of a muffler for control of noise pollution in a diesel engine
Authors: Ghosh B. B. , Chaudhury J , Banerjee T. K. , Ghosh A. K.
Published: October 2002

The present work aims at controlling the noise level of a diesel engine by developing an exhaust muffler for the same, since exhaust noise is the single largest contributor to the overall noise from the engine. The TATA 1210 six-cylinder diesel engine was considered for test purposes. A simulated design, developed by Ricardo with the application of the engine performance simulation program WAVE, was taken up, and this was modified in certain aspects to suit the engine under consideration. The muffler was fabricated and data were recorded for evaluation of the acoustic performance as well as the engine performance and for purposes of comparison with the existing muffler as well as with the open-ended exhaust system. The new muffler was found to be superior to the existing one in terms of both acoustic performance and engine performance. With the new muffler, the maximum noise reduction obtained was 19.3 dB(A) and the maximum brake thermal efficiency obtained was 39 per cent, while with the existing muffler the corresponding values were 14.5 dB(A)and 37.4 per cent. The present work has thus experimentally shown that results from WAVE can be modified and applied to an alternative design.
Exhaust pressure modelling for feedforward active control of internal combustion engine exhaust noise
Authors: Hong G
Published: October 2002

This paper reports work on modelling the exhaust noise pressure of a small single-cylinder spark ignition (SI) engine. The model will ultimately be used for on-line prediction of exhaust noise in an active control system with a single-error microphone. The frequency properties of the engine exhaust noise generated by this SI engine are characterized by harmonic components related to engine firing conditions. The frequencies of the harmonic components depend only on the engine firing frequency while the amplitudes of the harmonic components vary with the engine load. Twenty harmonic components at the lower frequency band were included to model the exhaust pressure pulse which is a two-dimensional function of engine speed and load. The model is represented by a double Chebyshev polynomial. The instantaneous exhaust pressure at steady state for a fixed position in the exhaust pipe was predicted using this model and compared with the experimental data. The result of this comparison is regarded as satisfactory.
Improvements in belt tension setting procedures on internal combustion engines
Authors: Fawcett J. N.
Published: October 2002

Current procedures for setting tensions in camshaft and auxiliary drive belts on the production line are analysed and improved methods proposed. These new methods allow for the effects of friction in the drive and belt hysteresis. The benefits of the improved procedure are demonstrated experimentally.
Influence of the resonant frequency on the control of knock in diesel engines
Authors: Ren Y , Randall R. B. , Milton B. E.
Published: October 2002

This paper presents an alternative approach to investigating the origin and the development process of knock vibrations that occur in an indirect injection (IDI) diesel engine. In contrast to the conventional analysis of the pressure rise rate, this study focuses on the analysis of instantaneous resonant frequencies at different moments during combustion. The smoothed pseudo-Wigner-Ville distribution (SPWVD) and Hilbert transform methods are applied to estimate the resonant frequency under different conditions representing various knock intensities. Two important factors are found significantly to influence knock development. Finally, design strategies and preferable fuel injection patterns are suggested for reducing knock intensity.
Experimental study into the energy absorbing characteristics of top-hat and double-hat sections subjected to dynamic axial crushing
Authors: White M. D. , Jones N
Published: October 2002

Dynamic axial crushing tests have been carried out on thin-walled top-hat and double-hat spot-welded mild steel sections which are used for structural crashworthy purposes in the automobile industry. Several post-test collapse modes were identified for the structures and the associated energy absorbing characteristics have been examined and compared with previous tests. A new empirical equation is suggested which relates the dynamic structural effectiveness to the structural density of top-hat and double-hat sections.
A new adaptive sky-hook control of vehicle semi-active suspensions
Authors: Yi K , Song B. S.
Published: October 2002

This paper proposes a new adaptive sky-hook control law for vehicle semi-active suspensions. Vehicle suspensions are disturbance-affected dynamic systems. In semi-active suspensions, damping coefficients are controlled so as to make the actual damper force as close to the desired damper force as possible at any time instance. The proposed control law consists of a ‘new adaptive’ sky-hook damping algorithm and a road detection algorithm (RDA). This approach leads to the sprung mass and unsprung mass velocity feedback control law with time varying gains. The gains are tuned by the RDA. To evaluate the performance enhancement brought about by the proposed control law, the performance of a semi-active suspension with the proposed control law is compared with that of the sky-hook controlled semi-active suspension and with a passive suspension. The controllers are implemented experimentally on a quarter-car test rig and a semi-active damper with 19 damping rates has been used to generate the desired semi-active force. The performance of the proposed control law is shown to be superior to that of the sky-hook control.
Prediction of transient nitric oxide in diesel exhaust
Authors: Chan S. H. , He Y , Sun J. H.
Published: October 2002

An extended Zeldovich mechanism, which models the kinetics of nitric oxide formation, is included in a multizone combustion model. The combustion model is subsequently integrated into a well-developed emptying and filling engine code to predict the transient nitric oxide emissions in the exhaust of a diesel engine. The predicted nitric oxide emissions, in terms of ppm level, have been validated satisfactorily with the experimental results obtained from a computer-controlled dynamic engine test bed on which a fully instrumented, turbocharged, direct injection (DI) diesel engine and a fast response regenerative d.c. dynamometer are mounted. The experimental results used in the comparison were reconstructed from the nitric oxide emission signals obtained by a conventional, slow response, chemiluminescence analyser.
Engagement behaviour of a paper-based wet clutch Part 1: Influence of drive torque
Authors: Holgerson M , Lundberg J
Published: October 2002

Owing to increasing demands when designing wet clutches for automatic transmissions, more knowledge about their behaviour is needed. In cars with power shifting automatic transmissions, an engine torque is continuously transmitted through the gear box. Most experimental and theoretical work concerning investigations of wet clutches today uses the inertia type of test apparatus, e.g. the SAE test machine 2. However, this type of test machine has no possibility of investigating the influence of a drive torque from the power supply.

In order to investigate the influence of drive torque on wet clutch engagements, a new type of apparatus was built, which can operate with different combinations of inertia and drive torque. This apparatus can perform engagements more similar to those in automatic transmissions.

The aim of this paper was to compare experimental outputs obtained using these principles of testing, concerning the influence of drive torque. It was found that the friction characteristics of wet clutches are independent of how the input energy is produced. This means that friction can be investigated with both principles. It was also found that an apparatus using only inertia gives shorter engagement times and higher temperatures than an apparatus including a drive torque at the same level of input energy. This can be explained by different power characteristics. Therefore, when investigating temperatures of wet clutch engagements, one must be careful when translating the results into reality.
Engagement behaviour of a paper-based wet clutch Part 2: Influence of temperature
Authors: Holgerson M , Lundberg J
Published: October 2002

To increase comfort, performance and fuel economy, a more careful optimization of automatic transmissions is needed. Of special interest is how the temperature influences the engagement characteristics. In order to increase the level of knowledge in this area, a wet clutch test rig including a drive torque and inertia was used. The temperature and the developed energy were varied in order to investigate their influence on the characteristics of an engagement. As a consequence the influence of instant temperature, maximum temperature and instant normal force was also studied. Some of the most important conclusions of the investigation are that both the dynamic and static friction coefficients slightly decrease and the engagement time increases with increasing temperature. It was also found that the static and dynamic friction coefficients are not influenced by energy if the instant temperature is the same. An important parameter that describes the risk of stick-slip is the quotient between the static and dynamic friction. It was found that this quotient decreases with increasing temperature, and thus the risk of stick-slip is also supposed to decrease.
Combustion characterization of natural gas in a lean burn spark-ignition engine
Authors: Rousseau S , Lemoult B , Tazerout M
Published: October 2002

Lean burn natural gas fuelled spark-ignition engines are particularly attractive regarding environmental performance. Nevertheless, few data exist concerning lean combustion in gas engines in terms of ignition delay, combustion duration and combustion rate. Such data are necessary when using thermodynamic models to predict energy and environmental performance. The present study proposes a contribution to such combustion characterization as a function of spark timing, air excess and engine load. This work is based on experimental cylinder pressure measurements in an open chamber engine on the one hand, and on a one-zone thermodynamic model used as a heat release analysis tool on the other hand. Results obtained, such as mass fraction burned, ignition delay and combustion duration, allow identification of the parameters used in the Wiebe function, a semi-empirical law that is frequently used to describe the combustion in predictive models.
Impact failure modes in glass structures
Authors: Grant P. V. , Cantwell W. J.
Published: October 2002

A range of glass-based structures of various constructions and thicknesses have been subjected to impact loading by stone chippings similar to those found on the roadside. The failure modes have been examined in an attempt to elucidate the failure mechanisms and processes in these systems. Initial tests generated radial and lateral cracking at velocities well above that required to initiate damage; this form of cracking was not observed again since attention was focused on the critical velocity for damage initiation. Thinner structures were found to fail primarily by star cracking, a flexure induced rear surface failure. Thicker structures generally failed by partial cone cracking, a contact induced front surface failure. The addition of a polymeric layer to the glass monolith had no effect on the failure mechanisms, while the addition of an inner layer of glass (yielding a laminated construction) had a secondary influence on the impact resistance of the structure. This was clearly apparent for intermediate outer glass thicknesses, where an increase in the inner glass thickness causes the stiffness of the panel to increase sufficiently to alter the failure mode and thus cause an increase in the critical velocity for damage initiation.
Reduction in machine noise and vibration levels based on the statistical energy analysis method
Authors: Cui D , Craighead I A
Published: October 2002

In noise and vibration control, damping treatment and isolation of structures are often applied to dissipate the energy of flexural vibrations and to reduce the transmission of energy to the surroundings. However, these treatments must be carefully designed because the present requirements of the size, power and noise levels resulting from commercial competition are very restrictive and usually there is little space to put additional material. In this paper, the statistical energy analysis (SEA) method has been used to optimize such treatment. The power balance equations have been established for a motor—fan—casing unit, and the design and possible modifications have been analysed with an SEA model. The energy transmission paths within the structure have been clearly identified and the test results confirmed the accuracy of this model. The optimum has been determined and lower noise levels have been verified by tests. A significant reduction in noise level has been achieved and the example has shown that an SEA model is very useful for analysing structures with regard to noise and vibration levels.
Preliminary determination of basic dimensions for an axial flow pump
Authors: Zaher M A , Ipenz M
Published: October 2002

One of the difficult tasks in axial flow pump design is the elaborate manner of predicting its correct dimensions. As more test data are accumulated, it depends upon the skill of the designer to discern the effects of these several variables, leading to the optimum hydraulic performance. In an attempt to contribute to saving time spent on determining the basic dimensions for an axial flow pump, a graphical method is proposed to assist in the preliminary determination of these dimensions.
Enhanced oil recovery using the rotating-disc skimmer
Authors: Najar A M , Turner J T
Published: October 2002

It is now common practice to use disc skimming systems to recover oil floating on the surface of water. However, the performance of these devices is dependent on a large number of parameters and is certainly not understood completely. This paper describes a fundamental study in which experimental techniques have been developed to enable the performance of model skimmers to be measured. This has enabled the importance of the various parameters to be examined in a more systematic and detailed way than ever before.

Based upon an improved understanding of the flow behaviour inherent in the oil collection process, a number of enhanced disc skimming systems are discussed. Results are presented for these systems to show the capabilities of the new forms of disc skimmer when operated as oil recovery devices.
Initial imperfections and the initiation of wrinkling in finite element modelling of deep drawing
Authors: Hematian J , Wild P M
Published: October 2002

The effect of initial imperfections on the initiation of wrinkling in finite element models of deep drawing operations is assessed. Models of an annular plate are subjected to radial in-plane loading and the effects of different types, magnitudes and distributions of imperfections are investigated. A model of a circular plate subjected to out-of-plane loading from a punch and die is similarly investigated and the results are compared with experimental data. It is confirmed that initial imperfections are an essential requirement for the initiation of wrinkling for the case of in-plane loading. Initial imperfections are shown to be unimportant in the initiation of wrinkling for the case of out-of-plane loading.
Using advanced modelling techniques to reduce the cold spillage from retail display cabinets into supermarket stores to maintain customer comfort
Authors: Foster A M , Quarini G L
Published: October 2002

Chilled foods are increasingly popular on supermarket shelves. For marketing reasons, chilled products are displayed in retail display cabinets where there is no physical barrier between the customer and the product. Cold air from the cabinet falls out of the cabinet on to the floor, causing the customer's feet to become cold, commonly known as the ‘cold feet’ effect.

The Ministry of Agriculture, Fisheries and Food (MAFF) funded a 3 year project to study the effects of retail display cabinets on supermarket store environments using experimental measurements and computational fluid dynamics. This paper provides an overview of the work and its findings.

Initially a computer model of the whole sales area of a supermarket store was numerically modelled. This proved to be too large to model small detail in the store and the time taken for convergence of the solution was too long to carry out many ‘what if’ scenarios in a limited time.

A smaller, more detailed model looking at just the coldest aisle (chilled produce aisle) was produced. This model was a good simulation of three different stores measured. The model was then used to predict the effect of different ventilation systems and did so with varying degrees of accuracy.
A production planning and design model for assessing the thermal behaviour of thick steel strip during continuous heat treatment
Authors: Morris W D
Published: October 2002

This paper presents a theoretical model to determine the temperature variation of steel strip as it passes through a continuous-cooling line. The model permits the temperature along the strip to be determined and includes the effect of strip thickness to be taken into account.

The model may be used in three ways. These are:

to determine the strip temperature distribution having specified the external surface heat transfer coefficient as a boundary condition and hence to specify the required length of the cooling line and the nature of the cooling technology appropriate to the thermal duty required to examine the effect of changing operational parameters, such as the strip thickness and line speed, on an existing cooling line so that required production rates are matched to the thermal characteristics of the line and to specify the distribution of the heat transfer coefficient along the cooling line in order to achieve a metallurgical prescribed timewise cooling history.

The paper includes a set of examples that illustrate these applications of the model.
Transient processes in a closed vessel due to injection of hot liquid sprays
Authors: Valha J , Lewis J S , Kubie J
Published: October 2002

An experimental and theoretical study has been made to investigate the transient processes which occur when hot liquid spray droplets are suddenly injected into a gas contained in a closed chamber. A novel experimental apparatus was employed in which hot water is injected via commercial solid cone spray nozzles into air enclosed in a cylindrical spray chamber, of 121 mm diameter and 190 mm height, at a pre-determined constant flowrate, and for a set duration, under computer control. Measurements were made of the spray chamber pressure rise with time due to the combined effects of liquid—gas heat transfer, droplet evaporation and liquid accumulation in the chamber. The experimental results reported in the paper cover a range of nozzle sizes, in both single-nozzle and multi-nozzle configurations, and the effects of liquid flowrate, initial gas pressure and initial liquid—gas temperature difference are considered. A simple analytical model has been developed which subdivides the chamber volume into three zones: a liquid zone, a transfer zone where heat and mass transfer occurs, defined by the spray cone angle, and a still zone outside the spray cone. The analysis gathers the important parameters governing droplet heat transfer in a single dimensionless group, denoted by K2. For the range of conditions investigated, reasonable agreement between the experimental results and the theoretical solutions were obtained with a value of K2 = 2 × 10−5.
Finite element and experimental analysis for the effect of elliptical chord shape on tubular T-joint strength
Authors: Hamed A F , Khalid Y A , Sahari B B , Hamdan M M
Published: October 2002

The strength of T-tubular joints with elliptical and circular cross-section tube chords with circular cross-section tube braces has been investigated. Experimental tests to determine the joint strength of these T-joints subjected to tension, compression, in-plane bending and out-of-plane bending loading cases have been carried out. A rig has been designed and built for that purpose. Three types of T-joint connections, namely type 1, type 2 and type 3, were selected. In type 1, the joint consisted of braces welded perpendicularly to the circular chord outer diameter, while for type 2 the brace had been welded perpendicularly to the elliptical chord minor diameter and for type 3 the brace has been welded perpendicularly to the elliptical chord major diameter. The chord has been held as fixed-fixed for all types. The material used in all tubes tested was mild steel. Throughout this investigation the ultimate loads and ultimate moments obtained from the tests have been converted to non-dimensional strength values for fair comparisons. Finite element models for similar T-joints for the three types were created and used under the same loading cases. Shell elements have been used to model the mesh required. An elastic analysis has also been carried out. The experimental results obtained show that type 3 joints are stronger than type 1 for all the loading modes. The increase in load and moment varies from 12.16 to 27.27 per cent. On the other hand, type 2 joints were found to be weaker than type 1 joints by 7.5-27.68 per cent for different loading modes. A comparison between experimental results and finite element analysis has also been made. It shows a percentage variation of 0.89-34.40 per cent. Another comparison with existing tubular joint design formulae showed that these formulae are conservative and highly safe for the geometry used.
Predicted influences of changes in particle size distribution in pulverized coal on attenuation of sound
Authors: Wang Q , Attenborough K , Woodhead S
Published: October 2002

Scattering theory predictions of the changes in the attenuation of sound at frequencies between 100 Hz and 100 kHz due to changes in the (spherical) particle size distributions in airborne particulate suspensions with characteristics typical of pulverized fuel flows are considered. These predictions are compared with a criterion for the detectability of insertion loss changes, assuming a sensor separation of 100 mm. It is concluded that, for such a separation, at frequencies greater than 30 kHz and concentrations greater than 0.5 kg/kg, it is feasible to monitor changes in the fraction of particles with radii above 37.5 μm by measuring cross-pipe sound attenuation.
Empirical relation for the effect of the shape of the capsules and the nose shape on the velocity ratio of heavy density capsules in a hydraulic pipeline
Authors: Agarwal V C , Singh M K , Mathur R
Published: October 2002

The velocity ratio of heavy density spherical, cylindrical, square and rectangular capsules is greatly dependent on the ratio of characteristic diameter to the diameter of capsule and the shape factor. The velocity ratio of heavy density cylindrical capsules having noses of different shapes is found to be dominantly dependent on the ratio of location of mass centre of the capsule to the diameter of capsule.
Applications of fault detection and diagnostic techniques for refrigeration and air conditioning: A review of basic principles
Authors: Halm-Owoo A K , Suen K O
Published: October 2002

During the 1990s a number of different prototype Refrigeration and Air Conditioning (RAC) Fault Detection and Diagnostic (FDD) systems have been developed and subsequently presented in various research publications. This interest in RAC FDD systems is generally a result of the potential benefits, such as reducing equipment downtime and avoiding energy wastage, these systems can bring to new and existing RAC installations. With the exception of a few reports produced by the International Energy Agency (IEA) Annex 25, no other publications or texts exist that bring together the various FDD concepts directly associated with RAC applications. However, the reports produced by the IEA are far from comprehensive enough to be of use to typical industry personnel. Therefore, the aim of this review is to present RAC personnel with a clearer understanding of the fundamental principles associated with the application of RAC FDD. The paper will initially highlight various relevant areas before presenting examples of typical FDD systems applicable to RAC systems.
Effect of viscous dissipation on laminar mixed convection in a horizontal channel
Authors: Salah El-Din M M
Published: October 2002

Laminar mixed convection in a horizontal channel is studied analytically in the fully developed region when the effect of viscous dissipation cannot be neglected. Two kinds of thermal boundary conditions are considered: uniform wall temperatures and uniform wall heat fluxes. Velocity and temperature profiles and the Nusselt numbers have been determined in a closed form. The results show that when viscous dissipation is taken into consideration, temperature profiles and Nusselt numbers are significantly affected by the Brinkman number while velocity profiles are independent of the Brinkman number.
Synthesis using fuzzy set theory and a Dempster—Shafer-based approach to compromise decision-making with multiple-attributes applied to risk control options selection
Authors: Sii H S , Ruxton T , Wang J
Published: October 2002

In decision-making there are always some parameters that are inaccurately known, meaning that the decision-making process must be based on subjective opinions. One of the useful aspects of fuzzy set theory is its ability to represent mathematically a class of decision problems called multiple objective decisions, with involvement of many vague (and thus fuzzy) goals and constraints. The objective of the fuzzy set decision methodology is to obtain an optimal decision in the sense that some set of goals is attained while observing (i.e., not violating) a simultaneous set of constraints. This paper presents a decision-making model as applied to multiple-attribute decision-making problems, which may be useful to decision-makers in many real-world problems. The proposed decision-making framework is a synthesis using an approach developed by Zadeh and Bellman in 1970 [1] and later extended by Yager, in 1977 [2], together with the Dempster—Shafer theory of evidence [3]. While dealing with a multiple-attribute decision-making problem the decision-maker may have to compromise with available alternatives, none of which may satisfy exactly his ultimate ideal best. The decision mechanism is constrained by the uncertainty and imprecision inherent in the determination of the relative importance of each attribute element and the classification of existing alternatives. The classification of alternatives is addressed through expert evaluation of the degree to which each attribute element is contained in each available alternative. The implementation of pairwise comparison and a ratio-scale quantification method by the decision-maker is performed to determine the relative importance of each attribute element. Then the ‘belief and plausibility’ that an alternative will satisfy the decision-maker's ideal ‘best’ are derived and combined to rank the available alternatives. Two examples in maritime safety engineering are presented to demonstrate the proposed framework.
Calculation of instantaneous sections in multi-axis milling
Authors: Vantomme P , Deprez P , Lefevre C , Castelain J M
Published: October 2002

Multi-axis milling is a technique that enables numerous machining applications, and in particular the finishing of complex surfaces (machining of moulds, matrices and prototypes). The high operational cost of multi-axis milling drives the suppliers of CAM software to develop simulation machining programs. Today, simulation machine tools integrate the ideas of trajectory and collision, but do not take into account the calculation of cutting speeds and cutting forces, or the calculation of stresses.

This paper is about the calculation of instantaneous sections in multi-axis milling, in order to model the cutting forces. All the models used to date have been formed on the principle of two circles set over from the feed movement by tooth for the calculation of the instantaneous section. For this study, the real travel of the tooth, which is a cycloid, will be taken into account.
In-line process monitoring for injection moulding control
Authors: Speight R G , Coates P D , Hull J B , Peters C
Published: October 2002

Injection moulding is one of the most important and efficient manufacturing techniques for polymeric materials, with the capability to manufacture high value added products. Integration of injection moulding machines into a computer integrated manufacturing (CIM) system requires reliable process monitoring allowing statistical process control (SPC) to be implemented. CIM systems are concerned with computer control and linking together of all functions in the manufacturing environment. Successful implementation of CIM requires accurate, reliable and meaningful information relating to all aspects of the manufacturing process. Hydraulic injection pressure measurements are shown to be important process parameters, indicating, with comparable precision to nozzle melt pressure, relative changes in polymer melt viscosity.
Investigations into decoating and recycling of pipeline elements using the on-site high-pressure water jet technique
Authors: Momber A W
Published: October 2002

The paper describes investigations into the application of the high-pressure water jet technique for the recycling of coated pipeline elements. The paper starts with the introduction and definition of the process parameter 'selectivity'. After this, a review about the general principles of jet cutting technology, including tools, is given. Finally, the author reports on the decoating and demolition of covered steel pipes by plain and abrasive water jets. High-pressure water jets are versatile tools for the complete and partial decoating of steel pipes. Abrasive water jets can be used successfully to cut steel pipes including different coating systems.
A finite element model of the electrofusion welding of thermoplastic pipes
Authors: Rosala G F , Day A J , Wood A S
Published: October 2002

An advanced finite element (FE) model of the electrofusion welding of thermoplastic pipes has been developed using the ABAQUS FE package. The heat transfer analysis is coupled with thermal deformation analysis to include the time-dependent closure of the initial gap between the pipe and fitting. The effect of radial melt movement into the interface is modelled using a new ‘virtual material movement’ technique. The predicted results (temperature distribution in the weld region, melt affected zones and gap closure time) are compared with experimental data and good agreement is found.
An experimental investigation into the detection of internal leakage of gases through valves by vibration analysis
Authors: Thompson G , Zolkiewski G
Published: October 2002

The theme of the paper is the detection of through-valve leakage by vibration analysis. Experiments have been performed which demonstrate that a valve leaking internally excites the downstream pipework at particular frequencies in the range below 20 kHz. Several frequencies are excited. However, of note is that certain frequencies appear to depend only on the internal diameter of the pipe and the properties of the gas leaking through the valve. The results of extensive experiments are presented and an empirical relationship is suggested to predict the frequencies excited by the leakage. Thus, there is potential for the use of this method in a valve condition monitoring system to augment the range of methods presently available, none of which find widespread application.
Experimental verification of a diagnostic model for reciprocating chillers
Authors: Ng K C , Chua H T , Ong A S
Published: October 2002

This paper investigates the robustness of a diagnostic model for the performance evaluation of reciprocating chillers. The model, which is described by three adjustable parameters of the chiller, is verified by experimental results with three purpose-built system configurations. It is found that the model is both flexible and accurate with respect to changes in the system layout and the predictions of chiller coefficients of performance (COP) are well within the experimental uncertainties.
Artificial intelligence based techniques for processing segmented images of wood boards
Authors: Pham D T , Alcock R J
Published: October 2002

Veneer boards are made by bonding together thin sheets of wood. Normally, grading of these sheets is carried out to ensure that only high-quality sheets are used to make high-quality boards. Frequently, this quality control task is performed by a human inspector. However, due to the speed and repetitive nature of the job, human graders cannot always grade the boards accurately. To improve the efficiency of grading, attempts are being made to automate it using automated visual inspection (AVI). Integral to the AVI process is segmentation, which is concerned with separating clear wood and defective areas in the image. The defective areas are labelled as segmented objects. However, after segmentation has been performed, two problems can occur. Firstly, clear wood areas may be falsely detected as defects and, secondly, a defect may be represented by more than one segmented object. This paper describes two techniques that have been used to overcome these problems. The techniques were inspired by the artificial intelligence (AI) techniques of fuzzy logic and self-organizing neural networks.
Investigation into the effect of circumferential through-wall slits on a cantilevered pipe subjected to a transverse end load
Authors: AI-Hassani S T S , Vartdal B
Published: October 2002

The main motive for carrying out the investigation is to explore the possibility of using slits to weaken the main legs of an offshore jacket structure as a means of creating a structural mechanism that facilitates safe and predictable toppling of offshore platforms. Cantilevered mild steel tubes containing through-wall circumferential slits are subjected to a transverse end load which causes the slit to open by hoop cracking. The effect of the slit geometry on the collapse characteristics of the tube is investigated experimentally and theoretically. A number of methods are used to predict the global load-deflection characteristics of the tube. These include a number of semiempirical methods based on the J integral and a numerical analysis utilizing the ABAQUS finite element code. The effective net section stress criterion is also used as a simple method of predicting the collapse load. This investigation has relevance to safety in chemical and nuclear plants.
The analysis of particle degradation in pneumatic conveyors utilizing a pilot-sized test facility
Authors: Bridle I , Woodhead S R , Reed A R
Published: October 2002

Pneumatic conveying systems are widely used to convey powdered and granular solid materials in industry. However, as with all transport methods, there are advantages and disadvantages to this technique. Product degradation can occur when using pneumatic transport. It is desirable to be able to predict product degradation in real pneumatic conveying systems at the design stage. At the moment this is very difficult to do from a fundamental viewpoint, due to the large number of variables involved, many of which are difficult to quantify for most systems. An empirical approach has therefore been adopted involving the development of a pilot-sized test facility. The test programme incorporated a series of tests using malted barley, granulated sugar and rice. This enabled the measurement of product degradation over a range of superficial air velocities (9-38 m/s), suspension densities and pipe bend geometries to be made for each material. This paper will present experimental results obtained from the pilot-sized rig, indicating and discussing the effects of a number of variables on degradation.