Zhengyan Zhang and Sanjay Joshi
This paper aims to develop a slice-based representation of geometry and material information of a multi-material object to be produced by additive manufacturing. Representation of…
Abstract
Purpose
This paper aims to develop a slice-based representation of geometry and material information of a multi-material object to be produced by additive manufacturing. Representation of complex heterogeneous material allowing for the additive manufacturing-based build of a wide range of objects that are limited only by the constraints of the manufacturing process.
Design/methodology/approach
Initial 3D CAD models are created with multiple and functionally graded materials using an assembly model to create a single part with well-defined material regions. These models are then sliced to create the geometry and material boundaries required for each layer to enable layer-by-layer fabrication.
Findings
A representation schema is proposed to add multi-material attributes to a sliced file for additive manufacturing using the combination of material index and material geometry region. A modified common layer interface data format is proposed to allow for representation of a wide range of homogeneous and heterogeneous material for each slice. This format allows for a generic input for tool paths to be generated for each material of the layer.
Originality/value
The proposed approach allows for slice data representation for any material combination that can be defined mathematically. Three different material types, namely, composite material, functionally graded materials and combination thereof, are provided as examples. These data form the input data for subsequent tool path planning.
Details
Keywords
In order to represent, analyze, optimize, and manufacture a component made of multi‐heterogeneous materials for high‐tech applications, a computer model of the heterogeneous…
Abstract
In order to represent, analyze, optimize, and manufacture a component made of multi‐heterogeneous materials for high‐tech applications, a computer model of the heterogeneous component needs to be built first. Heterogeneous materials include composite, functionally graded materials, and heterogeneous materials with a periodic microstructure. Current modeling techniques focus only on capturing the geometric information and cannot satisfy the requirements from modeling the components made of multi‐heterogeneous materials. This paper develops a modeling method, which can be implemented by employing the functions of current CAD graphic software and can obtain the model including both the material information (about its microstructures and constituent composition) and the geometry information without the problems arising from too many data.
Details
Keywords
Xiaojun Wu, Weijun Liu and Michael Yu Wang
The representation of Heterogeneous Object (HO) is divided into two categories: Data model (DM) and material evaluation paradigm (MEP). A hybrid methodology with geometry model…
Abstract
The representation of Heterogeneous Object (HO) is divided into two categories: Data model (DM) and material evaluation paradigm (MEP). A hybrid methodology with geometry model and volumetric dataset to represent heterogeneous properties is proposed in this paper. Geometry model of an object can guarantee the accuracy of the final HO slices; and volumetric dataset lends the flexible manipulability and other advantages to HO representation. Two MEPs, namely distance field (DF) based and Fixed Reference Features & Active Grading Source(s) (FRF&AGS) are presented to facilitate the process of HO representation according to the designer)s input parameters. The DM can be modified interactively with users until the final satisfactory result is obtained. In this paper, a scheme of HO slicing is described. In this method, we utilize the slices contour of geometrical model as constraint to reconstruct the HO slices, which can theoretically achieve the same accuracy with the geometrical shape. Some examples of Heterogeneous object represented with our scheme are provided.
Details
Keywords
This paper presents a modeling scheme for objects containing multiple materials or functionally graded materials (FGM), i.e. heterogeneous objects. The material composition…
Abstract
This paper presents a modeling scheme for objects containing multiple materials or functionally graded materials (FGM), i.e. heterogeneous objects. The material composition variations under this modeling scheme are controlled by some reference features termed as “grading sources”. The “grading source” gathers the type of grading, position of grading and a material grading function for controlling the material transitions and a union operation is defined for interacting between different grading sources.
Details
Keywords
Apart from the geometries to be dealt with, rapid prototyping (RP) of heterogeneous objects requires additional material information to be processed. This generally involves a…
Abstract
Purpose
Apart from the geometries to be dealt with, rapid prototyping (RP) of heterogeneous objects requires additional material information to be processed. This generally involves a large amount of information to be processed simultaneously. The robustness and efficiency problems, which seem less critical in homogeneous solid fabrications, become an issue. The direct impetus of this paper is to present robust and efficient algorithms for RP of heterogeneous objects.
Design/methodology/approach
The robustness is benefited from using the proposed non‐manifold heterogeneous cellular model, which guarantees gap‐free material depositions around material interfaces. The efficiency enhancement is achieved by eliminating repetitive boundary intersections and using a heuristic material interrogation approach.
Findings
By using the proposed algorithms, the robustness and efficiency of RP of heterogeneous objects can be improved. It is found that an average 30 percent efficiency improvement is obtained using the proposed heuristic material interrogation approach.
Originality/value
Non‐manifold heterogeneous cell representation (HC‐Rep) is used in RP fields for the first time. Based on the HC‐Rep, the robustness and efficiency of RP of heterogeneous object is addressed in this paper.
Details
Keywords
This paper identifies and discusses that parks, as one kind of open space, must be open not only for some people, but for everyone, including those with special needs such as…
Abstract
Purpose
This paper identifies and discusses that parks, as one kind of open space, must be open not only for some people, but for everyone, including those with special needs such as visually impaired people. The paper further identifies a number of key directions for the policy, design and management of park environments and facilities that will promote openness and social inclusion.
Design/methodology/approach
The study was qualitative in nature. Case study approach on park environments and facilities was adopted. Used site studies, field observations, interviews with the government officials and professionals of planners, designers and management were conducted. Direct interviews with the visually impaired people were conducted during the field observation. Some of them were also invited to participate in participatory research workshops to give comments and suggestions on the design and management of park environments and facilities.
Findings
Open spaces are important and necessary for all. However, visually impaired people are always indirectly excluded from open spaces such as parks, which are important for the quality of urban life. Three areas that require attention to improve the accessibility of parks: ways of identifying and approaching the parks; overall environmental setting of the parks; and facilities inside the parks. Assistance to visually impaired people can be further categorized into information provided in advance and information provided on-site.
Research limitations/implications
Further case studies are expected to be conducted in other kinds of open space and other cities in order to generate a more comprehensive understanding related to the topic. Continuous studies are also necessary since the park environments and facilities are changing all the time. With the users ' participation, in particular those with special needs, in research is important.
Practical implications
The findings provide reference and direction for the governments, designers and managment to plan, design and manage parks for the needs of visually impaired people. The findings also advocate inclusive and universal approach in planning, implementation and management of parks.
Social implications
The findings identify that visually impaired people most of the time are indirectly excluded from accessing parks as well as other open spaces.
Originality/value
Although the paper was based on a case study in Hong Kong, its practical and social implications are also important to other places. Although barrier-free concept and requirement have been enforced in many places for some years, people with special needs (in particular visually impaired people) still face a lot of “barriers” in their daily life. The findings provide insights for researchers and also policymakers, designers and management to review the needs of the visually impaired.
Details
Keywords
The purpose of this study is to examine the causal relationship between per capita electricity consumption (PCEC) and per capita gross national income (GNI) (PCGNI) in Bangladesh…
Abstract
Purpose
The purpose of this study is to examine the causal relationship between per capita electricity consumption (PCEC) and per capita gross national income (GNI) (PCGNI) in Bangladesh for the period of 1971-2014.
Design/methodology/approach
Vector error correction modeling approach.
Findings
The study reveals that positive short-run unidirectional causal flow running between PCEC to PCGNI without feedback which implies that an increase in electricity consumption promptly affects economic activity. The results of both long-run and joint causality yield strong evidence of bidirectional causal relationship between PCEC and per capita real GNI with feedback.
Originality/value
Therefore, both electricity generation and conservation policy will be effective for Bangladesh economy. So, smooth supply of electricity is necessary to meet the growing electricity demand for consumption; consequently, it will lead to sustain of growth and take it even higher level.
Details
Keywords
Katherine Kent, Yan Hin Siu, Melinda Hutchesson, Clare Collins and Karen Charlton
This study aims to understand university students' perception and engagement with sustainable food practices and the relationship with diet quality.
Abstract
Purpose
This study aims to understand university students' perception and engagement with sustainable food practices and the relationship with diet quality.
Design/methodology/approach
A cross-sectional survey assessed Australian university students' sustainable food perceptions and purchasing behaviours, diet quality using the validated Australian Recommended Food Score and attitudes towards on campus sustainable food options.
Findings
Of respondents (n = 197; 63% female), over half (58%) perceived it was important to purchase sustainable foods. These students were eight times more likely report purchasing sustainable foods (OR: 8.1; 95%CI 4.2–15.7; SE: 0.3; p < 0.001) and had significantly higher diet quality (Beta coefficient: 2.9; 95% Confidence Intervals 0.4–5.4; Standard Error: 1.3; p = 0.024). Students who reported frequently purchasing all types of sustainable foods, except organic foods, had significantly higher diet quality. Few students perceived there were sufficient sustainable food choices on campus (19%), but most supported the development of an edible campus (80%).
Originality/value
The results highlight the potential impact of promoting sustainable food options and creating a supportive campus food environment towards improving students’ diet quality.
Details
Keywords
Sima Rani Dey and Mohammed Tareque
The purpose of this paper is to assess the empirical cointegration, long-run and short-run dynamics as well as causal relationship between electricity consumption and real GDP in…
Abstract
Purpose
The purpose of this paper is to assess the empirical cointegration, long-run and short-run dynamics as well as causal relationship between electricity consumption and real GDP in Bangladesh for the period of 1971‒2014.
Design/methodology/approach
Autoregressive Distributed lag (ARDL) “Bound Test” approach is employed for the investigation in this study.
Findings
Both short-run and long-run coefficients are providing strong evidence of having positive significant association between electricity consumption and GDP. Our long-run results remain robust to different measurements and estimators as well. The study reveals the unidirectional causal flow running from per capita electricity consumption to per capita real GDP in the short run. The study result also yields strong evidence of bidirectional causal relationship between per capita electricity consumption and per capita real GDP in the long run with feedback. It is suggested that both electricity generation and conservation policy will be effective for Bangladesh economy.
Originality/value
In prior studies, lack of causality between electricity consumption and GDP is due to the omitted variables. Combined effects of public spending and trade openness on GDP and electricity consumption are also considerable.
Details
Keywords
Abstract
A processing algorithm for freeform fabrication of heterogeneous structures is presented. The algorithm was developed based on the heterogeneous fabrication structural model, which was constructed from the STL based multi‐material volume regions and with material identifications. The reasoning Boolean operation based modelling approach was used to construct the heterogeneous CAD assembly and to output the needed STL format. Procedures for generating the database hierarchy and the storage of the heterogeneous structural model, and derivation for developing the processing algorithm for layered fabrication of heterogeneous structure are presented. The developed algorithm was applied to a heterogeneous structure consisting of two discrete material volumes, and the detailed processing path is described.