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1 – 10 of over 45000Sadegh Rahmati, Farid Abbaszadeh and Farzam Farahmand
The purpose of this paper is to present an improved methodology for design of custom‐made hip prostheses, through integration of advanced image processing, computer aided design…
Abstract
Purpose
The purpose of this paper is to present an improved methodology for design of custom‐made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies.
Design/methodology/approach
The proposed methodology for design of custom‐made hip prostheses is based on an independent design criterion for each of the intra‐medullary and extra‐medullary portions of the prosthesis. The intra‐medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra‐medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance is achieved. The extra‐medullary portion of the prosthesis is designed based on the anatomical features of the femoral neck, in order to restore the original biomechanical characteristics of the hip joint. The whole design procedure is implemented in a systematic framework to provide a fast, repeatable and non‐subjective response which can be further evaluated and modified in a preplanning simulation environment.
Findings
The efficacy of the proposed methodology for design of custom‐made hip prostheses was evaluated in a case study on a hip dysplasia patient. The cortical bone was distinguished from cancellous in CT images using a thresholding procedure. In particular the septum calcar ridge could be recognized and was incorporated in the design to improve the primary stability of the prosthesis. The lateral and frontal views of the prosthesis, with the patient's images at the background, indicated a close geometrical match with the cortical bone of femoral shaft, and a good compatibility with the anatomy of the proximal femur. Also examination of the cross sections of the prosthesis and the patient's intra‐medullary canal at five critical levels revealed close geometrical match in distal stem but less conformity in proximal areas due to preserving the septum calcar ridge. The detailed analysis of the fitting deviation between the prosthesis and point cloud data of the patient's femoral intra‐medullary canal, indicated a rest fitting deviation of 0.04 to 0.11 mm in stem. However, relatively large areas of interference fit of −0.04 mm were also found which are considered to be safe and not contributing to the formation of bone cracks. The geometrical analysis of the extra‐medullary portion of the prosthesis indicated an anteversion angle of 12.5 degrees and a neck‐shaft angle of 131, which are both in the acceptable range. Finally, a time and cost effective investment casting technique, based on AM technology, was used for fabrication of the prosthesis.
Originality/value
The proposed design methodology helps to improve the fixation stability of the custom made total hip prostheses and restore the original biomechanical characteristics of the joint. The fabrication procedure, based on AM technology, enables the production of the customized hip prosthesis more accurately, quickly and economically.
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Hilary Davies and Graham Wilmshurst
Surveyors, who may be involved in specifying retro‐fitted cavityinsulation, need to know the key factors which influence the potentialrisk of rain penetration. Proposes guidance…
Abstract
Surveyors, who may be involved in specifying retro‐fitted cavity insulation, need to know the key factors which influence the potential risk of rain penetration. Proposes guidance for surveyors to undertake a low‐cost initial visual survey and desk study as a first stage in the assessment of a dwelling′s suitability for retro‐fitted cavity insulation. A case‐study of low‐rise housing on a local authority estate on the south coast of England, which has retro‐fitted cavity insulation, allowed the identification of these key factors and testing of their statistical significance. Factors identified are aspect towards prevailing wind and driving rain index; exposure (related to local topographic and sheltering features); wall impermeability; and any factors of particular significance to the site. If an individual dwelling has a combination of these factors, it is likely to have a 60 per cent increased risk of rain penetration.
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This article describes the Employment Service approach to the use of benchmarking as a tool by looking at how it was used to improve a key human resource area ‐ internal vacancy…
Abstract
This article describes the Employment Service approach to the use of benchmarking as a tool by looking at how it was used to improve a key human resource area ‐ internal vacancy filling. It covers: leadership ‐ why we decided to use benchmarking as a performance improvement tool and high level sponsorship of the project; methods ‐ the process benchmarking approach used ‐ internal, industry and generic; and results, business, customer satisfaction and organisational learning. The article concludes that benchmarking can be effectively applied in the area of human resources and can lead to significant improvements in performance. It shows how the benchmarking approach leads to individual, team and organisational learning.
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A stressed skin leading edge structure for aircraft wings and the like; comprising a unitary metal sheet formed to define a spanwise extending hollow leading edge structure of…
Abstract
A stressed skin leading edge structure for aircraft wings and the like; comprising a unitary metal sheet formed to define a spanwise extending hollow leading edge structure of aerofoil cross section, a preformed core of low density material separately shaped to fit and completely fill the hollow interior of said leading edge structure and forming the sole support for said skin, a layer of air drying adhesive between the interior surface of said metal sheet and the exterior surface of said core, the rear edges of said metal sheet being supported by spanwise extending stiffeners adapted to define faying edges for attaching said leading edge structure to the centre section of an aircraft wing or the like.
The purpose of this paper is to present a new simplified local remeshing procedure for the study of discrete crack propagation in finite element (FE) mesh. The proposed technique…
Abstract
Purpose
The purpose of this paper is to present a new simplified local remeshing procedure for the study of discrete crack propagation in finite element (FE) mesh. The proposed technique accounts for the generation and propagation of crack‐like failure within an FE‐model. Beside crack propagation, the technique enables the analysis of fragmentation of initially intact continuum. The capability of modelling fragmentation is essential in various structure‐structure interaction analyses such as projectile impact analysis and ice‐structure interaction analysis.
Design/methodology/approach
The procedure combines continuum damage mechanics (CDM), fictitious crack approach and a new local remeshing procedure. In the approach a fictitious crack is replaced by a discrete crack by applying delete‐and‐fill local remeshing. The proposed method is independent of mesh topology unlike the traditional discrete crack approach. The procedure is implemented for 3‐D solid elements in commercial finite element software Abaqus/Explicit using Python scripting. The procedure is completely automated, such that crack initiation and propagation analyses do not require user intervention. A relatively simple constitutive model was implemented strictly for demonstrative purposes.
Findings
Well known examples were simulated to verify the applicability of the method. The simulations revealed the capabilities of the method and reasonable correspondence with reference results was obtained. Material fragmentation was successfully simulated in ice‐structure interaction analysis.
Originality/value
The procedure for modelling discrete crack propagation and fragmentation of initially intact quasi‐brittle materials based on local remeshing has not been presented previously. The procedure is well suited for simulation of fragmentation and is implemented in a commercial FE‐software.
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Diana Irinel Baila, Filippo Sanfilippo, Tom Savu, Filip Górski, Ionut Cristian Radu, Catalin Zaharia, Constantina Anca Parau, Martin Zelenay and Pacurar Razvan
The development of new advanced materials, such as photopolymerizable resins for use in stereolithography (SLA) and Ti6Al4V manufacture via selective laser melting (SLM…
Abstract
Purpose
The development of new advanced materials, such as photopolymerizable resins for use in stereolithography (SLA) and Ti6Al4V manufacture via selective laser melting (SLM) processes, have gained significant attention in recent years. Their accuracy, multi-material capability and application in novel fields, such as implantology, biomedical, aviation and energy industries, underscore the growing importance of these materials. The purpose of this study is oriented toward the application of new advanced materials in stent manufacturing realized by 3D printing technologies.
Design/methodology/approach
The methodology for designing personalized medical devices, implies computed tomography (CT) or magnetic resonance (MR) techniques. By realizing segmentation, reverse engineering and deriving a 3D model of a blood vessel, a subsequent stent design is achieved. The tessellation process and 3D printing methods can then be used to produce these parts. In this context, the SLA technology, in close correlation with the new types of developed resins, has brought significant evolution, as demonstrated through the analyses that are realized in the research presented in this study. This study undertakes a comprehensive approach, establishing experimentally the characteristics of two new types of photopolymerizable resins (both undoped and doped with micro-ceramic powders), remarking their great accuracy for 3D modeling in die-casting techniques, especially in the production process of customized stents.
Findings
A series of analyses were conducted, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, mapping and roughness tests. Additionally, the structural integrity and molecular bonding of these resins were assessed by Fourier-transform infrared spectroscopy–attenuated total reflectance analysis. The research also explored the possibilities of using metallic alloys for producing the stents, comparing the direct manufacturing methods of stents’ struts by SLM technology using Ti6Al4V with stent models made from photopolymerizable resins using SLA. Furthermore, computer-aided engineering (CAE) simulations for two different stent struts were carried out, providing insights into the potential of using these materials and methods for realizing the production of stents.
Originality/value
This study covers advancements in materials and additive manufacturing methods but also approaches the use of CAE analysis, introducing in this way novel elements to the domain of customized stent manufacturing. The emerging applications of these resins, along with metallic alloys and 3D printing technologies, have brought significant contributions to the biomedical domain, as emphasized in this study. This study concludes by highlighting the current challenges and future research directions in the use of photopolymerizable resins and biocompatible metallic alloys, while also emphasizing the integration of artificial intelligence in the design process of customized stents by taking into consideration the 3D printing technologies that are used for producing these stents.
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If one consults an up‐to‐date list of approximate tests issued by a wholesale lubricating oil concern the following kind of item will be encountered : “150 Solv. Neut. Redwood…
Abstract
If one consults an up‐to‐date list of approximate tests issued by a wholesale lubricating oil concern the following kind of item will be encountered : “150 Solv. Neut. Redwood viscosity at 70°F. 310″, at 140°F. 66″”. The grade number refers to a Saybolt reading and the viscosities are in Redwood seconds. But this is 19G2 and we are well in the kinematic era. Yet reference to empirical viscosity units is by no means uncommon. Brooding on this prompted the author to recall something of efflux viscometers, the transition to the capillary instrument and the persistance of an earlier tradition.
In an aircraft the combination with an engine and a propeller of streamlining devices comprising a streamlined spinner section rotatably mounted on the engine shaft forward of the…
Abstract
In an aircraft the combination with an engine and a propeller of streamlining devices comprising a streamlined spinner section rotatably mounted on the engine shaft forward of the propeller, means to inhibit rotation of said spinner with the shaft, a streamlined section movable with the propeller and constituting a continuation of the streamlining of the spinner section, a streamlined fixed section secured to the engine and constituting a continuation of the spinner and rotatable streamlined section and a cowling surrounding and secured to the engine and formed to provide a narrow air inlet slot between said cowling and the fixed section to admit a limited flow of air about the engine and outlets for the exit of said air, said cowling including outlets for the exit of substantially all the air entering said inlet slot.
Jalal M. Alattar, Reza Kouhy and John Innes
Relatively little research exists about the information used by owner/managers (O/Ms) in micro enterprises (less than 10 employees). The purpose of this paper is to explore the…
Abstract
Purpose
Relatively little research exists about the information used by owner/managers (O/Ms) in micro enterprises (less than 10 employees). The purpose of this paper is to explore the management accounting information (MAI) generated and used by O/Ms for planning, decision making and control in micro manufacturing enterprises in the Gaza Strip (GS).
Design/methodology/approach
A grounded theory approach is used with case studies being the main research method.
Findings
Three main themes emerged during the five case studies. Firstly, how is the generation and use of MAI related to the O/M, enterprise and environmental features? Secondly, what is the impact of formal or informal procedures on the generation and use of MAI? Thirdly, what is the extent of written and oral MAI generated and used? From the five individual case studies 133 findings emerged and then a cross‐case analysis generated 21 overall findings.
Research limitations/implications
The case studies excluded micro enterprises less than three years old, micro enterprises with more than one O/M and micro enterprises from sectors other than manufacturing.
Originality/value
This project explores what impact various factors (such as political uncertainty, competition and the need for cost reduction) have on the generation and use of MAI in micro enterprises. Several findings are particularly relevant for O/Ms of micro enterprises in developing countries. Previous studies have not identified to what extent written or oral MAI is generated and used for each of the core business aspects of micro manufacturing enterprises.
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Bolanle Felicia Adegoke and Oluseyi Joshua Adegoke
The purpose of this paper is to investigate the use of facilities management in selected tertiary institutions in Osun State, Nigeria. This is with a view to giving needed…
Abstract
Purpose
The purpose of this paper is to investigate the use of facilities management in selected tertiary institutions in Osun State, Nigeria. This is with a view to giving needed attention to the built environment in the tertiary institutions in Nigeria in order to make them more conducive for learning.
Design/methodology/approach
The study used purposive sampling technique to select four tertiary institutions out of six in the study area. A total of 60 questionnaires were distributed to obtain information from construction professionals in works and physical planning departments of the selected institutions. The selected institutions are Obafemi Awolowo University, Ile‐Ife, Ladoke Akintola University, Ogbomoso, The Federal Polytechnic, Ede and Osun State College of Technology, Esa Oke. Both descriptive and inferential statistical methods of analysis were used to analyse the data.
Findings
The results revealed that the in‐house maintenance technique, which was mostly used, was found to be inefficient whereas the outsourcing and the one‐site technique, which were scarcely used, were found to be more efficient. Also, it was revealed that outsourcing reduces risk due to reliance on experts and infusion of new technology.
Practical implications
The study concluded that the use of the outsourcing and one‐site techniques should be embraced to upgrade and sustain the built environment for conducive learning.
Originality/value
The study is an attempt to stop the magnitude into which the built environment in the tertiary institutions of Nigeria is deteriorating, before becoming unconducive for learning.
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