434 research outputs found
Comparison of Volumetric Analysis Methods for Machine Tools with Rotary Axes
Confidence in the ability of a production machine to meet manufacturing
tolerances requires a full understanding of the accuracy of the machine.
However, the definition of âthe accuracy of the machineâ is open to
interpretation. Historically, this has been in terms of linear positioning accuracy
of an axis with no regard for the other errors of the machine. Industry awareness
of the three-dimensional positioning accuracy of a machine over its working
envelope has slowly developed to an extent that people are aware that
âvolumetric accuracyâ gives a better estimation of machine performance.
However, at present there is no common standard for volumetric errors of
machine tools, although several researchers have developed models to predict
the effect of the combined errors.
The error model for machines with three Cartesian axes has been well
addressed, for example by the use of homogenous transformation matrices.
Intuitively, the number of error sources increases with the number of axes
present on the machine. The effect of the individual axis geometric errors can
become increasingly significant as the chain of dependent axes is extended.
Measurement of the âvolumetric errorâ or its constituents is often restricted
to a subset of the errors of the Cartesian axes by solely relying on a laser
interferometer for measurement. This leads to a volumetric accuracy figure that
neglects the misalignment errors of rotary axes. In more advanced models the
accuracy of the rotary axes are considered as a separate geometric problem
whose volumetric accuracy is then added to the volumetric accuracy of the
Cartesian axes.
This paper considers the geometric errors of some typical machine
configurations with both Cartesian and non-Cartesian axes and uses case studies
to emphasise the importance of measurement of all the error constituents.
Furthermore, it shows the misrepresentation when modelling a five-axis
machine as a three-plus-two error problem. A method by which the five-axis
model can be analysed to better represent the machine performance is
introduced.
Consideration is also given for thermal and non-rigid influences on the
machine volumetric accuracy analysis, both in terms of the uncertainty of the
model and the uncertainty during the measurement. The magnitude of these
errors can be unexpectedly high and needs to be carefully considered whenever
testing volumetric accuracy, with additional tests being recommended
Frequencies of Lipopolysaccharide Core Types among Clinical Isolates of Escherichia coli Defined with Monoclonal Antibodies
Mouse monoclonal antibodies (MAbs) specific for the lipopolysaccharide (LPS) core types R1, R2, and R3 of Escherichia coli and a cross-reactive MAb that binds to the LPS core of almost all E. coli were used in ELISA to determine the frequency of cores resembling R1, R2, and R3 in strains of E. coli isolated from clinical samples (blood and urine specimens) and from the feces of asymptomatic individuals. Of the 180 wild-type isolates, 123 were assigned to R1 core type, 14 to R2, and 18 to R3. Twenty-five wild-type E. coli isolates could not be assigned to a particular core type and may have either an R4 or K12 core or a previously unrecognized core type. R1 core type was associated with O types 1, 4, 6, 8, and 18 and with K1 or K5 capsules. R3 was associated with O15.O75 isolates could be of either R1 or R2 core typ
Developing resources to facilitate culturally-sensitive service planning and delivery â doing research inclusively with people with learning disabilities
Background Black, Asian and minority ethnic people with learning disabilities face inequities in health and social care provision. Lower levels of service uptake and satisfaction with services have been reported, however, this is largely based on the views of carers. The âAccess to Social Care: Learning Disabilities (ASC-LD)â study sought to explore the views and experiences of social support services among adults with learning disabilities from Black, Asian and minority ethnic communities. Interviews with 32 Black, Asian and minority ethnic adults with learning disabilities were conducted to explore participantsâ cultural identities, their understanding and experience of âsupportâ. The views and experiences expressed in the ASC-LD study were used in the âTools for Talking projectâ to develop a suite of resources designed to facilitate culturally-sensitive communication and information-sharing, service planning and delivery through improved mutual understanding between providers and users of services. This paper describes the Tools for Talking project which sought to co-develop the resources through a partnership event. Methods An inclusive approach was adopted to address issues that are important to people with learning disabilities, to represent their views and experiences, and to involve Black, Asian and minority ethnic people with learning disabilities in the research process. Partnerships were developed with provider organisations and service users who were invited to a âPartnership Eventâ. Collaborators at the partnership event were asked to comment on and evaluate draft resources which included a series of videos and activities to explore topics that emerged as important in the ASC-LD study. Their comments were collated and the tools developed as they suggested. Results Using the results from the ASC-LD study helped to ensure that the draft resources were relevant to service users, addressing topics that were important to them. The partnership event was an effective method to collaborate with a relatively large number of stakeholders. However, the event was resource intensive and required substantial planning to ensure active and meaningful participation. Considerations, such as inviting stakeholders, developing the programme and selecting a venue are discussed. Conclusions The partnership approach has led to the development of a set of five illustrative videos and accompanying activities that address issues that emerged from the collaborative process including: culture, activities, support from staff, important people, choices and independence. These resources are freely available at: www.Toolsfortalking.co.uk. They are designed to be used by users and providers of services, but may also be useful in other settings
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