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Article
Publication date: 8 May 2018

Aibin Zhu, Hongling Wu, Yulei Yang and Shengli He

Because of the various geometric descriptions of different bearing types, performance calculation of journal bearing is complicated, and is difficult in traditional model…

Abstract

Purpose

Because of the various geometric descriptions of different bearing types, performance calculation of journal bearing is complicated, and is difficult in traditional model. This paper aims to simplify the calculation of the journal bearing performance, and to reduce the workload.

Design/methodology/approach

On the basis of previous research, a general performance calculation model of journal bearing is proposed in this paper. Eccentricity ratio and attitude angle of axis to each pad are calculated by coordinates of spindle center and each pad center by establishing the unified coordinate system. The surface deformation of journal bearing is taken into consideration, and a correction value is added to the dimensionless oil film thickness.

Findings

The performance calculation results of various fix-pad and tilting-pad journal bearings match the results of the existing references very well, revealing the validity of the model. The general model can greatly reduce programming workload, and increase adaptability to different bearings.

Originality/value

Geometric descriptions of both fix-pad and tilting-pad journal bearings are unified in this model, which can be applied to both standard and non-standard journal bearings with different preload ratios. In addition, due to the unification of different bearings types, this model is more conducive to performance comparison among different bearing types, and promotes the development of new structural forms for journal bearings.

Details

Industrial Lubrication and Tribology, vol. 70 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 22 July 2021

Farhad Sadeghineko and Bimal Kumar

Facilitating the information exchange and interoperability between stakeholders during the life-cycle of an asset can be one of the fundamental necessities for developing…

Abstract

Purpose

Facilitating the information exchange and interoperability between stakeholders during the life-cycle of an asset can be one of the fundamental necessities for developing an enhanced information exchange framework. Such a framework can also improve the successful accomplishment of building projects. This paper aims to use Semantic Web technologies for facilitating information exchange within existing building projects.

Design/methodology/approach

In real-world building projects, the construction industry’s information supply chain may initiate from near scratch when new building projects are started resulting in diverse data structures represented in unstructured data sources, like Excel spreadsheets and documents. Large-scale data generated throughout a building's life-cycle requires exchanging and processing during an asset's Operation and Maintenance (O&M) phase. Building information modelling (BIM) processes and related technologies can address some of the challenges and limitations of information exchange and interoperability within new building projects. However, the use of BIM in existing and retrofit assets has been hampered by the challenges surrounding the limitations of existing technologies.

Findings

The aim of this paper is twofold. Firstly, it briefly outlines the framework previously developed for generating semantically enriched 3D retrofit models. Secondly, a framework is proposed focussing on facilitating the information exchange and interoperability for existing buildings. Semantic Web technologies and standards, such as Web Ontology Language and existing AEC domain ontologies are used to enhance and improve the proposed framework.

Originality/value

The proposed framework is evaluated by implementing an example application and the Resource Description Framework data produced by the previously developed framework. The proposed approach makes a valuable contribution to the asset/facilities management (AM/FM) domain. It should be of interest to various FM practices for existing assets, such as the building information/knowledge management for design, construction and O&M stages of an asset’s life-cycle.

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Article
Publication date: 18 October 2018

Zhicheng Huang, Jean-Yves Dantan, Alain Etienne, Mickaël Rivette and Nicolas Bonnet

One major problem preventing further application and benefits from additive manufacturing (AM) nowadays is that AM build parts always end up with poor geometrical quality…

Abstract

Purpose

One major problem preventing further application and benefits from additive manufacturing (AM) nowadays is that AM build parts always end up with poor geometrical quality. To help improving geometrical quality for AM, this study aims to propose geometrical deviation identification and prediction method for AM, which could be used for identifying the factors, forms and values of geometrical deviation of AM parts.

Design/methodology/approach

This paper applied the skin model-based modal decomposition approach to describe the geometrical deviations of AM and decompose them into different defect modes. On that basis, the approach to propose and extend defect modes was developed. Identification and prediction of the geometrical deviations were then carried out with this method. Finally, a case study with cylinders manufactured by fused deposition modeling was introduced. Two coordinate measuring machine (CMM) machines with different measure methods were used to verify the effectiveness of the methods and modes proposed.

Findings

The case study results with two different CMM machines are very close, which shows that the method and modes proposed by this paper are very effective. Also, the results indicate that the main geometrical defects are caused by the shrinkage and machine inaccuracy-induced errors which have not been studied enough.

Originality/value

This work could be used for identifying and predicting the forms and values of AM geometrical deviation, which could help realize the improvement of AM part geometrical quality in design phase more purposefully.

Details

Rapid Prototyping Journal, vol. 24 no. 9
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 December 1963

H.L. Price

SECTION (B). GEOMETRIC ASPECTS OF TRIMMED FLIGHT The Relation Between the Various Planes of Reference The preceding analytical investigation of the trimmed conditions has…

Abstract

SECTION (B). GEOMETRIC ASPECTS OF TRIMMED FLIGHT The Relation Between the Various Planes of Reference The preceding analytical investigation of the trimmed conditions has been based upon the use of the particular set of axes advocated in Part I. There we took as the dominant axis the axis of the rotor shaft, and regarded as the dominant plane, plane RS, the plane perpendicular to the rotor shaft. We recall that the choice of this plane as a plane of reference was dictated by the importance attached at the outset to the study of the dynamics of the blade motion. We also pointed out that, from the mechani‐cal point of view, plane SP, the plane of the swash‐plate for in the absence of a swash‐plate, the equivalent ‘plane of no‐feathering’), could alterna‐tively be regarded as the dominant reference plane. But now we sec that if we concentrate on the aerodynamic aspect, the prevalence of the ex‐pressions (?i—?0+?0?1) and (?1—?) ascribe prime importance to the axis of the flapping cone. Now just as in the case of the rotor shaft, we chose to specify its direction by a plane perpendicular to it, so here we shall specify the axis of the flapping cone by any plane perpendicular to it. One such plane is the tip‐path plane: another is the plane through the rotor hub parallel to the tip‐path plane. We shall refer to cither plane as the plane TP, and so long as we are only concerned with directions, no ambiguity will be caused. We now have three planes competing for attention, planes RS, SP and TP, and it is our object to link these planes together and see what roles they play in the description of the motion of the helicopter as a whole, having special regard in all this to the particular position of the helicopter's C.G. It may be added that the relationship between these planes is a prominent feature of certain papers [Refs. (2), (10)], and the phrase ‘the equivalence of flapping and feathering’ is there used to describe the resultant findings. It will be shown that there are two different interpretations of this phrase, and that in one sense, what is implied is no more than the equivalence of alternative geometric descriptions of one and the same motion of a helicopter rotor. On the other hand, the phrase may be taken to mean that a rotor having no flapping hinge at all [such as the one analysed by Squire in Ref. (3)] performs effectively in the same way as one free to flap. Indeed, the results of Ref. (3) are frequently used as the basis of many trim and stability calculations of helicopters with freely flapping rotors, despite the lack of a flapping hinge in the calculations of Ref. (3). We shall see that, in general, this procedure is questionable.

Details

Aircraft Engineering and Aerospace Technology, vol. 35 no. 12
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 26 June 2019

Xiufeng Cheng, Jinqing Yang, Ling Jiang and Anlei Hu

The purpose of this paper is to introduce an interpreting schema and semantic description framework for a collection of images of Xilankapu, a traditional Chinese form of…

Abstract

Purpose

The purpose of this paper is to introduce an interpreting schema and semantic description framework for a collection of images of Xilankapu, a traditional Chinese form of embroidered fabric and brocade artwork.

Design/methodology/approach

First, the authors interpret the artwork of Xilankapu through Gillian Rose’s “four site” theory by presenting how the brocades were made, how the patterns of Xilankapu are classified and the geometrical abstraction of visual images. To further describe the images of this type of brocade, this paper presents semantic descriptions that include objective–non-objective relations and a multi-layered semantic framework. Furthermore, the authors developed corresponding methods for scanning, storage and indexing images for retrieval.

Findings

As exploratory research on describing, preserving and indexing images of Xilankapu in the context of the preservation of cultural heritage, the authors collected 1,000+ images of traditional Xilankapu, classifying and storing some of the images in a database. They developed an index schema that combines concept- and content-based approaches according to the proposed semantic description framework. They found that the framework can describe, store and preserve semantic and non-semantic information of the same image. They relate the findings of this paper to future research directions for the digital preservation of traditional cultural heritages.

Research limitations/implications

The framework has been designed especially for brocade, and it needs to be extended to other types of cultural image.

Originality/value

The semantic description framework can describe connotative semantic information on Xilankapu. It can also assist the later information retrieval work in organizing implicit information about culturally related visual materials.

Details

The Electronic Library , vol. 37 no. 3
Type: Research Article
ISSN: 0264-0473

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Article
Publication date: 1 April 1998

Dimitrios Tsoubelis

It is often impossible to study a geometric surface that lacks an analytic description. However, using computer graphics techniques it is now feasible to visualize such…

Abstract

It is often impossible to study a geometric surface that lacks an analytic description. However, using computer graphics techniques it is now feasible to visualize such implicitly defined surfaces; hence initiate their study. A typical example of such surfaces is the ones defined as “the locus of points that satisfy a set of conditions”. These conditions are usually distance relationships between geometric entities such as a point, a line, a plane etc. For example, a paraboloid is defined as “the locus of points in 3‐D that are equi‐distant from a plane and a given point”. In this work, we present a way for modelling and visualizing implicit surfaces. We demonstrate our approach with the construction and subsequent visualization of generalized weighted Voronoi tessellation using as control points simple geometric objects.

Details

Kybernetes, vol. 27 no. 3
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 1 December 1994

Chin‐Sheng Chen and Jintong Wu

Addresses the need for a unified product information model and presentsa new representation scheme for mechanical component modelling usingshells as its principal geometric

Abstract

Addresses the need for a unified product information model and presents a new representation scheme for mechanical component modelling using shells as its principal geometric primitives for modelling form features. The representation scheme was implemented using the ACIS geometric modeller and C++ on a SUN SPARC/10 station. The advantage of using shells is that both surface and volume information of a form feature can be derived from a shell. Different levels of product data representation can be integrated into a single model. Therefore, it allows the user to model the geometry effectively and form features of a mechanical part on one system.

Details

Integrated Manufacturing Systems, vol. 5 no. 4/5
Type: Research Article
ISSN: 0957-6061

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Article
Publication date: 8 January 2018

Mahmood Reza Khabbazi, Jan Wikander, Mauro Onori and Antonio Maffei

This paper introduces a schema for the product assembly feature data in an object-oriented and module-based format using Unified Modeling Language (UML). To link…

Abstract

Purpose

This paper introduces a schema for the product assembly feature data in an object-oriented and module-based format using Unified Modeling Language (UML). To link production with product design, it is essential to determine at an early stage which entities of product design and development are involved and used at the automated assembly planning and operations. To this end, it is absolutely reasonable to assign meaningful attributes to the parts’ design entities (assembly features) in a systematic and structured way. As such, this approach empowers processes such as motion planning and sequence planning in assembly design.

Design/methodology/approach

The assembly feature data requirements are studied and definitions are analyzed and redefined. Using object-oriented techniques, the assembly feature data structure and relationships are modeled based on the identified requirements as five UML packages (Part, three-dimensional (3D) models, Mating, Joint and Handling). All geometric and non-geometric design data entities endorsed with assembly design perspective are extracted or assigned from 3D models and realized through the featured entity interface class. The featured entities are then associated (used) with the mating, handling and joints features. The AssemblyFeature interface is realized through mating, handling and joint packages related to the assembly and part classes. Each package contains all relevant classes which further classify the important attributes of the main class.

Findings

This paper sets out to provide an explanatory approach using object-oriented techniques to model the schema of assembly features association and artifacts at the product design level, all of which are essential in several subsequent and parallel steps of the assembly planning process, as well as assembly feature entity assignments in design improvement cycle.

Practical implications

The practical implication based on the identified advantages can be classified in three main features: module-based design, comprehensive classification, integration. These features help the automation and solution development processes based on the proposed models much easier and systematic.

Originality/value

The proposed schema’s comprehensiveness and reliability are verified through comparisons with other works and the advantages are discussed in detail.

Details

Assembly Automation, vol. 38 no. 1
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 1 February 1978

YU. ANTOMONOV and A. KOTOVA

The equations take into account structural and geometrical parameters (sizes and a configuration of the synapse, geometrical properties of the neuron membrane, local…

Abstract

The equations take into account structural and geometrical parameters (sizes and a configuration of the synapse, geometrical properties of the neuron membrane, local changes of concentrations and potential) and determine changes of concentrations and the potential on the membrane and in hemispheres for discrete areas of the cytoplasm and the adjacent membrane part. Their investigation demonstrated that the equations may form the basis of sufficiently complete neuron description with due allowance for the fundamental physico‐chemical laws of motion and for the structural properties of separate parts of the nerve‐cell.

Details

Kybernetes, vol. 7 no. 2
Type: Research Article
ISSN: 0368-492X

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Article
Publication date: 16 June 2010

E. Carrera and A. Robaldo

The purpose of this paper is to present several two‐dimensional plate elements for the analysis of shear actuated laminate.

Abstract

Purpose

The purpose of this paper is to present several two‐dimensional plate elements for the analysis of shear actuated laminate.

Design/methodology/approach

The limitations of the classical formulations based on the principle of virtual displacements in depicting the peculiar behavior of the transverse and normal stresses of multilayered structures have been easily overcome by using the mixed variational theorem proposed by Reissner (Reissner mixed variational theorem). In the framework of a unified formulation (UF), the assumptions of the unknowns is made through a common expansion leading both to global and layerwise description of the assumed unknowns. In addition, the possibility to choose the order of the expansion between one and four allows to be derived and compared 22 different plate models. The performances of the proposed elements have tested on application for whom an exact solution is available in open literature.

Findings

The obtained results complain quite well with the exact ones even if the need of advanced plate models come to evidence.

Originality/value

This paper describes how the capabilities of the UF to accurately analyze multilayered structures exploiting the shear mode actuation have been tested and states that in order to extend the capabilities of the UF, further efforts should be made toward the assumptions of discontinuous electric fields (potential and normal displacement). The paper confirms the need for advanced higher order plate models in modeling of adaptive laminate.

Details

Multidiscipline Modeling in Materials and Structures, vol. 6 no. 1
Type: Research Article
ISSN: 1573-6105

Keywords

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