L. Brennan, J. Browne, B.J. Davies, M.E.J. O'Kelly and A.R. Gault
Recently, there has been considerable interest in the EEC in overtime working. In these times of high unemployment, some commentators have suggested that a reduction in overtime…
Abstract
Recently, there has been considerable interest in the EEC in overtime working. In these times of high unemployment, some commentators have suggested that a reduction in overtime working could lead to job creation. This study attempts to look at reasons for overtime working as seen by management and to assess the potential for a reduction in overtime working in a policy of work sharing. It is in two parts, the first gives a summary of the results of a national level sample survey among managers of firms in the Republic of Ireland while the second part describes the use of a simulation model to test decisions relating to overtime working in an engineering job shop in the United Kingdom. The two sections complement one another and give insights into the behaviour of managers in relation to overtime working. It should be noted that the views of workers or of legislators are not reported. The views of workers would, of course, be very important in relation to the possibility of the successful implementation of a policy of reduced overtime working.
L. Brennan, F. Finnan and M.E.J. O'Kelly
The requirements for two smaller companies in integratedmanufacturing are addressed, in particular, the area of manufacturingcontrol. The functional areas pertaining to…
Abstract
The requirements for two smaller companies in integrated manufacturing are addressed, in particular, the area of manufacturing control. The functional areas pertaining to manufacturing control in both companies are reviewed. On the basis of these reviews and management objectives, their requirements are specified. Recommendations are then made in respect of both companies on how to meet these requirements having regard to the nature of the manufacturing control systems available.
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Extended from the classic Rayleigh damping model in structural dynamics, the Caughey damping model allows the damping ratios to be specified in multiple modes while satisfying the…
Abstract
Purpose
Extended from the classic Rayleigh damping model in structural dynamics, the Caughey damping model allows the damping ratios to be specified in multiple modes while satisfying the orthogonality conditions. Despite these desirable properties, Caughey damping suffers from a few major drawbacks: depending on the frequency distribution of the significant modes, it can be difficult to choose the reference frequencies that ensure reasonable values for all damping ratios corresponding to the significant modes; it cannot ensure all damping ratios are positive. This paper aims to present a constrained quadratic programming approach to address these issues.
Design/methodology/approach
The new method minimizes the error of the structural displacement peak based on the response spectrum theory, while all modal damping ratios are constrained to be greater than zero.
Findings
Several comprehensive examples are presented to demonstrate the accuracy and effectiveness of the proposed method, and comparisons with existing approaches are provided whenever possible.
Originality/value
The proposed method is highly efficient and allows the damping ratios to be conveniently specified for all significant modes, producing optimal damping coefficients in practical applications.
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L. Brennan, P. Claffey, J. Dineen and M.E.J. O'Kelly
Electronic sub‐assemblies are now a common feature of many products. The final output of production in areas such as computers, consumer goods, instrumentation and…
Abstract
Electronic sub‐assemblies are now a common feature of many products. The final output of production in areas such as computers, consumer goods, instrumentation and telecommunications equipment contain one or more electronic sub‐assemblies. Electronic sub‐assemblies are complex components built from smaller components such as Integrated Circuits (ICs) assembled on to Printed Circuit Boards (PCBs). Testing is an important but non‐productive part of the process of electronic sub‐assembly. However, it is a means of cost avoidance and ultimately a requirement for staying in business.
J. Browne and B.J. Davies
Much research has been reported on the possibilities of using various heuristic priority rules to sequence batches through a job shop. The SPT (Shortest Priority Time) heuristic…
Abstract
Much research has been reported on the possibilities of using various heuristic priority rules to sequence batches through a job shop. The SPT (Shortest Priority Time) heuristic, or modifications to it, has been proved useful in many studies. This paper reports on the results obtained when simulating the work flow through a real machine shop. The simulation model has been used to test the effect on well known priority rules of releasing batches into the shop in order of decreasing expected throughput time. The important effect of this “phased release” of batches was to increase the percentage of batches delivered in finished parts stores on time, particularly in the case where priority rules were in use which might otherwise have resulted in poor delivery. This has important repercussions for management because it implies that by “phased” release of batches in the manner discussed, a large proportion of batches will be delivered on time whatever priority rule is in operation in the shop.
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F.A. DiazDelaO and S. Adhikari
In the dynamical analysis of engineering systems, running a detailed high‐resolution finite element model can be expensive even for obtaining the dynamic response at few frequency…
Abstract
Purpose
In the dynamical analysis of engineering systems, running a detailed high‐resolution finite element model can be expensive even for obtaining the dynamic response at few frequency points. To address this problem, this paper aims to investigate the possibility of representing the output of an expensive computer code as a Gaussian stochastic process.
Design/methodology/approach
The Gaussian process emulator method is discussed and then applied to both simulated and experimentally measured data from the frequency response of a cantilever plate excited by a harmonic force. The dynamic response over a frequency range is approximated using only a small number of response values, obtained both by running a finite element model at carefully selected frequency points and from experimental measurements. The results are then validated applying some adequacy diagnostics.
Findings
It is shown that the Gaussian process emulator method can be an effective predictive tool for medium and high‐frequency vibration problems, whenever the data are expensive to obtain, either from a computer‐intensive code or a resource‐consuming experiment.
Originality/value
Although Gaussian process emulators have been used in other disciplines, there is no knowledge of it having been implemented for structural dynamic analyses and it has good potential for this area of engineering.
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Cellular manufacturing is the organisation of manufacturingequipment based on the requirements of the product or component.Transition to cellular manufacturing generally requires…
Abstract
Cellular manufacturing is the organisation of manufacturing equipment based on the requirements of the product or component. Transition to cellular manufacturing generally requires reorganisation of existing equipment. It is likely that the existing equipment alone is not suitable for a cellular layout. During the cell planning and design phase equipment investment analysis is important to identify equipment needs. Transition from job shop production to cellular production is detailed. Cell formation and cell evaluation techniques are provided to assist in equipment procurement decisions. In particular, a structured procedure and analytical tools are given to evaluate fully the cellular system to identify appropriate equipment and methods. A case example is provided to explain the procedure.