In the undergraduate engineering course at the University of Cambridge six graphics terminals are... more In the undergraduate engineering course at the University of Cambridge six graphics terminals are being used to teach 500 undergraduates by packages and routines especially designed for unsupervised operation by men in their first and second years. Topics covered include closed-loop control systems, slider mechanisms, projection theory, intersection of surfaces, elastic and plastic collapse and vibrating systems. Ordinary display facilities are also available for use by undergraduates, research students and teaching staff. The terminals are installed in the students’ drawing office directly alongside the normal drawing boards and are in full-time use. The choice of a flat bed plotter and teleprinter as a terminal has been proved wise for teaching and economy. Gradual expansion into other areas of teaching and research is taking place, and the introduction of CAD methods, not as a separate subject but as an integral part of the normal Cambridge Engineering degree course, is proceeding smoothly and with enthusiasm from teaching staff and undergraduates alike.
IEE Seminar on Tools for Simulation and Modelling, 2000
ABSTRACT The software package Dymola, which implements the new, vendor-independent standard model... more ABSTRACT The software package Dymola, which implements the new, vendor-independent standard modelling language Modelica, exemplifies the emerging generation of object-oriented modelling and simulation tools. This paper shows how, in addition to its simulation capabilities, it may be used as an embodiment design tool, to automatically size a design assembled from a library of generic parametric components. The example used is a miniature model aircraft diesel engine. To this end, the component classes contain extra algebraic equations for calculating the overload factor (or its reciprocal, the safety factor) for all the different failure modes, such as buckling or tensile yield. Thus, the simulation results contain the maximum overload or the minimum safety factor for each failure mode, along with the critical instant and the device state at which it occurs. The Dymola “Initial Conditions Calculation” function, controlled by a simple software script, may then be used to perform automatic component sizing. Each component is minimised in mass, subject to a chosen safety factor against failure, over a given operating cycle. Whilst the example is in the realm of mechanical design, it must be emphasised that the approach is equally applicable to the electrical or mechatronic domains, indeed to any design problem requiring numerical constraint satisfaction
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1992
A matrix-based method is presented for calculating velocities and accelerations in two- and three... more A matrix-based method is presented for calculating velocities and accelerations in two- and three-dimensional mechanisms. The method involves no symbolic manipulation or differentiation and is comparatively simple to implement as a computer algorithm, in that the same arithmetic process is used regardless of the configuration of the mechanism, and regardless of its complexity. The quantity of computation varies linearly with the number of moving parts in the mechanism.
<jats:title>Abstract</jats:title> <jats:p>Many designs fail because one or more... more <jats:title>Abstract</jats:title> <jats:p>Many designs fail because one or more checks are not done, or are done too late during the design process. A functional modelling system is presented, which provides systematic design checking at early design phases by means of constraint satisfaction. However, problems can occur if the design to be checked involves too many constraints.</jats:p> <jats:p>This paper presents some extended research, which establishes a knowledge hierarchy for managing the mathematical constraints, so that the computer can process large designs. A case study of fastening joint design using this hierarchy is discussed.</jats:p>
The feasible solution space for a mechanical engineering design is determined by the variables an... more The feasible solution space for a mechanical engineering design is determined by the variables and constraints involved in the design. Although constraint satisfaction programs can be used to find individual solutions in this space, their search strategies become very inefficient if the search space is much larger than the solution space. The user then cannot be sure whether a prolonged unsuccessful search is due to this inherent inefficiency, or because no solution space actually exists. In addition, such programs provide no information about the amount by which a satisfactory design solution can be adjusted without violating any constraints. This paper presents the implementation of a computer program which utilises a domain propagation algorithm to estimate the feasible design space. The theoretical descriptions of domain propagation and the algorithm are also discussed. Case studies show that this program enhances the efficiency and robustness of the constraint-based design proc...
PurposeThis paper aims to explore the information needs and information-seeking behaviours of the... more PurposeThis paper aims to explore the information needs and information-seeking behaviours of the new generation of engineering designers. A survey study is used to approach what their information needs are, how these needs change during an engineering design project and how their information-seeking behaviours have been influenced by the newly developed information technologies (ITs). Through an in-depth analysis of the survey results, the key functions have been identified for the next-generation management systems.Design/methodology/approachThe paper first proposed four hypotheses on the information needs and information-seeking behaviours of young engineers. Then, a survey study was undertaken to understand their information usage in terms of the information needs and information-seeking behaviours during a complete engineering design process. Through analysing the survey results, several findings were obtained and on this basis, further comparisons were made to discuss and eval...
In the global market of air transport, integration of products and services is now seen as being ... more In the global market of air transport, integration of products and services is now seen as being necessary for the long-term success of engine manufacturers. This paper describes research stimulated by a fundamental shift that is occurring in the manufacture and marketing of aero engines for commercial and defence purposes, away from the selling of products to the provision of services. Our collaborating aerospace company now offers TotalCare TM contracts, under which it leases engines to airlines while remaining responsible for their maintenance. The aims of our ongoing research are to: (1) understand the current flows of in-service information to designers; (2) understand the in-service information requirements of designers; (3) develop, based on this understanding, the most appropriate theories and methods to support designers in their new task. The work presented in this paper aims at understanding the use of in-service information in a design task by examining the executed desi...
This research is triggered by the emerging 'power by the hour'® paradigm, in which aero e... more This research is triggered by the emerging 'power by the hour'® paradigm, in which aero engines are effectively leased to airlines, with the manufacturing company remaining responsible for their maintenance and repair throughout their service life. By incorporating knowledge about the performance of existing products into the design phase of new products, it is hoped to tackle some of the in-service problems at the design stage. In the aerospace sector, it is standard design practice to utilise the experience gained from past projects, but that from in-service has not been given sufficient attention. In this context, the aims of our ongoing research are: (1) to understand the current flows of in-service information to designers; (2) to understand the in-service information requirements of designers; (3) to develop the most appropriate theories and methods to support designers in their new task of creating engines which will perform reliably and economically throughout their ...
In the undergraduate engineering course at the University of Cambridge six graphics terminals are... more In the undergraduate engineering course at the University of Cambridge six graphics terminals are being used to teach 500 undergraduates by packages and routines especially designed for unsupervised operation by men in their first and second years. Topics covered include closed-loop control systems, slider mechanisms, projection theory, intersection of surfaces, elastic and plastic collapse and vibrating systems. Ordinary display facilities are also available for use by undergraduates, research students and teaching staff. The terminals are installed in the students’ drawing office directly alongside the normal drawing boards and are in full-time use. The choice of a flat bed plotter and teleprinter as a terminal has been proved wise for teaching and economy. Gradual expansion into other areas of teaching and research is taking place, and the introduction of CAD methods, not as a separate subject but as an integral part of the normal Cambridge Engineering degree course, is proceeding smoothly and with enthusiasm from teaching staff and undergraduates alike.
IEE Seminar on Tools for Simulation and Modelling, 2000
ABSTRACT The software package Dymola, which implements the new, vendor-independent standard model... more ABSTRACT The software package Dymola, which implements the new, vendor-independent standard modelling language Modelica, exemplifies the emerging generation of object-oriented modelling and simulation tools. This paper shows how, in addition to its simulation capabilities, it may be used as an embodiment design tool, to automatically size a design assembled from a library of generic parametric components. The example used is a miniature model aircraft diesel engine. To this end, the component classes contain extra algebraic equations for calculating the overload factor (or its reciprocal, the safety factor) for all the different failure modes, such as buckling or tensile yield. Thus, the simulation results contain the maximum overload or the minimum safety factor for each failure mode, along with the critical instant and the device state at which it occurs. The Dymola “Initial Conditions Calculation” function, controlled by a simple software script, may then be used to perform automatic component sizing. Each component is minimised in mass, subject to a chosen safety factor against failure, over a given operating cycle. Whilst the example is in the realm of mechanical design, it must be emphasised that the approach is equally applicable to the electrical or mechatronic domains, indeed to any design problem requiring numerical constraint satisfaction
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1992
A matrix-based method is presented for calculating velocities and accelerations in two- and three... more A matrix-based method is presented for calculating velocities and accelerations in two- and three-dimensional mechanisms. The method involves no symbolic manipulation or differentiation and is comparatively simple to implement as a computer algorithm, in that the same arithmetic process is used regardless of the configuration of the mechanism, and regardless of its complexity. The quantity of computation varies linearly with the number of moving parts in the mechanism.
<jats:title>Abstract</jats:title> <jats:p>Many designs fail because one or more... more <jats:title>Abstract</jats:title> <jats:p>Many designs fail because one or more checks are not done, or are done too late during the design process. A functional modelling system is presented, which provides systematic design checking at early design phases by means of constraint satisfaction. However, problems can occur if the design to be checked involves too many constraints.</jats:p> <jats:p>This paper presents some extended research, which establishes a knowledge hierarchy for managing the mathematical constraints, so that the computer can process large designs. A case study of fastening joint design using this hierarchy is discussed.</jats:p>
The feasible solution space for a mechanical engineering design is determined by the variables an... more The feasible solution space for a mechanical engineering design is determined by the variables and constraints involved in the design. Although constraint satisfaction programs can be used to find individual solutions in this space, their search strategies become very inefficient if the search space is much larger than the solution space. The user then cannot be sure whether a prolonged unsuccessful search is due to this inherent inefficiency, or because no solution space actually exists. In addition, such programs provide no information about the amount by which a satisfactory design solution can be adjusted without violating any constraints. This paper presents the implementation of a computer program which utilises a domain propagation algorithm to estimate the feasible design space. The theoretical descriptions of domain propagation and the algorithm are also discussed. Case studies show that this program enhances the efficiency and robustness of the constraint-based design proc...
PurposeThis paper aims to explore the information needs and information-seeking behaviours of the... more PurposeThis paper aims to explore the information needs and information-seeking behaviours of the new generation of engineering designers. A survey study is used to approach what their information needs are, how these needs change during an engineering design project and how their information-seeking behaviours have been influenced by the newly developed information technologies (ITs). Through an in-depth analysis of the survey results, the key functions have been identified for the next-generation management systems.Design/methodology/approachThe paper first proposed four hypotheses on the information needs and information-seeking behaviours of young engineers. Then, a survey study was undertaken to understand their information usage in terms of the information needs and information-seeking behaviours during a complete engineering design process. Through analysing the survey results, several findings were obtained and on this basis, further comparisons were made to discuss and eval...
In the global market of air transport, integration of products and services is now seen as being ... more In the global market of air transport, integration of products and services is now seen as being necessary for the long-term success of engine manufacturers. This paper describes research stimulated by a fundamental shift that is occurring in the manufacture and marketing of aero engines for commercial and defence purposes, away from the selling of products to the provision of services. Our collaborating aerospace company now offers TotalCare TM contracts, under which it leases engines to airlines while remaining responsible for their maintenance. The aims of our ongoing research are to: (1) understand the current flows of in-service information to designers; (2) understand the in-service information requirements of designers; (3) develop, based on this understanding, the most appropriate theories and methods to support designers in their new task. The work presented in this paper aims at understanding the use of in-service information in a design task by examining the executed desi...
This research is triggered by the emerging 'power by the hour'® paradigm, in which aero e... more This research is triggered by the emerging 'power by the hour'® paradigm, in which aero engines are effectively leased to airlines, with the manufacturing company remaining responsible for their maintenance and repair throughout their service life. By incorporating knowledge about the performance of existing products into the design phase of new products, it is hoped to tackle some of the in-service problems at the design stage. In the aerospace sector, it is standard design practice to utilise the experience gained from past projects, but that from in-service has not been given sufficient attention. In this context, the aims of our ongoing research are: (1) to understand the current flows of in-service information to designers; (2) to understand the in-service information requirements of designers; (3) to develop the most appropriate theories and methods to support designers in their new task of creating engines which will perform reliably and economically throughout their ...
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Papers by Aylmer L Johnson