Dong Wang, Jun Wu, Liping Wang, Yuzhe Liu and Guang Yu
The purpose of this paper is to describe and evaluate the time-varying and coupling dynamic characteristics of a 3-DOF parallel tool head.
Abstract
Purpose
The purpose of this paper is to describe and evaluate the time-varying and coupling dynamic characteristics of a 3-DOF parallel tool head.
Design/methodology/approach
From the view of control, a new dynamic index of a 3-DOF parallel tool head is proposed based on the dynamic model in the joint space. This index can reflect the time-varying and coupling dynamic characteristics which are the main characteristics of the parallel mechanisms, and its distribution in the whole workspace is also given. Through comparison of the dynamic load (driving current) of each driving shaft, a series of experiments is designed and carried out on a prototype to validate the effectiveness of the dynamic analysis. The tracking error of each driving shaft has also been taken into consideration.
Findings
The simulations of the index have the same variation law with the experimental results. The dynamic load of the driving shaft becomes larger with the increase of the dynamic index, and the dynamic performance becomes worse at the same time.
Originality/value
The main dynamic characteristics of the 3-DOF parallel tool head can be described and evaluated through this work.
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Yuzhe Liu, Jun Wu, Liping Wang, Jinsong Wang, Dong Wang and Guang Yu
The purpose of this study is to develop a modified parameter identification method and a novel measurement method to calibrate a 3 degrees-of-freedom (3-DOF) parallel tool head…
Abstract
Purpose
The purpose of this study is to develop a modified parameter identification method and a novel measurement method to calibrate a 3 degrees-of-freedom (3-DOF) parallel tool head. This parallel tool head is a parallel mechanism module in a five-axes hybrid machine tool. The proposed parameter identification method is named as the Modified Singular Value Decomposition (MSVD) method. It aims to overcome the difficulty of choosing the algorithm parameter in the regularization identification method. The novel measurement method is named as the vector projection (VP) method which is developed to expand the measurement range of self-made measurement implements.
Design/methodology/approach
Newton Iterative Algorithm based on Least Square Method is analyzed by using the Singular Value Decomposition method. Based on the analysis result, the MSVD method is proposed. The VP method transforms the angle measurement into the displacement measurement by taking full advantage of the ability that the 3-DOF parallel tool head can move in the X – Y plane.
Findings
The kinematic calibration approach is verified by calibration simulations, a Rotation Tool Center Point accuracy test and an experiment of machining an “S”-shaped test specimen.
Originality/value
The kinematic calibration approach with the MSVD method and VP method could be successfully applied to the 3-DOF parallel tool head and other 3-DOF parallel mechanisms.
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Abstract
Purpose
This paper aims to design and optimize the threaded fastener of leakage current particulate matter (PM) sensor. The corresponding air-tight test is conducted to ensure the reliability of the installation strategy with screw connection.
Design/methodology/approach
Research on the pressure-deformation curve of seal gasket was conducted and the vibration load of engine was considered for the calculation of the minimum installation pre-tightening force. Simultaneously, the danger threaded section area was calculated, and the carrying capacity was verified. The height of the welding line was studied to ensure the reliability of the application. FEA was carried out to acquire the relationship between local structure size and local stress for continuous improvement of thread connection. The installation torque range was acquired from the torque control principle for the pre-tightening force. The sealing reliability of the connector was proved with leakage.
Findings
The air tightness of the thread connector is proved to be fine. When the pre-tightening force is over 8,000 N, and its length reaches 2 mm, the connector has good reliability at ambient temperature. The tightening torque of 60-74 Nm can guarantee the reliable fixing ability of thread connector, and its plastic non-deformation ability in the process of repeated tearing down.
Originality/value
This paper provides an installation strategy and an optimization of PM sensor, which has a positive effect on the study and the manufacture of PM sensor. It is helpful to further develop PM sensor and after-treatment technology. This kind of real-time monitoring PM sensor needs to be studied further to achieve its commercial application.
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The purpose of this paper is to analyze the structure and changes of China’s land system. To achieve this aim, the paper is divided into four parts. The first part gives a brief…
Abstract
Purpose
The purpose of this paper is to analyze the structure and changes of China’s land system. To achieve this aim, the paper is divided into four parts. The first part gives a brief introduction to the structural characteristics of the Chinese land institutional arrangements; the second part analyzes the reform process of the land system in the past 40 years and its path of change; the third part engages the discussion about the historic contribution made by the land institutional change to rapid economic growth and structural changes; and the final part is conclusion and some policy implications.
Design/methodology/approach
After 40 years of reforms and opening up, China has not only created a growth miracle unparalleled for any major country in human history, but also transformed itself from a rural to an urban society. Behind this great transformation is a systemic reform in land institutions. Rural land institutions went from collectively owned to household responsibility system, thereby protecting farmers’ land rights. This process resulted in long-term sustainable growth in China’s agriculture, a massive rural-urban migration and a historical agricultural transformation. The conversion of agricultural land to non-agricultural uses and the introduction of market mechanisms made land a policy tool in driving high economic growth, industrialization and urbanization.
Findings
Research shows that the role of land and its relationship with the economy will inevitably change as China’s economy enters a new stage of medium-to-high speed growth. With economic restructuring, low-cost industrial land will be less effective. Urbanization is also shifting from rapid expansion to endogenous growth so that returns on land capitalization will decrease and risks will increase. Therefore, China must abandon land-dependent growth model through deepening land reforms and adapt a new pattern of economic development.
Originality/value
This paper gives a brief introduction to the structural characteristics of the Chinese land institutional arrangements, analyzes the reform process of the land system in the past 40 years and its path of change, and evaluates the historic contribution made by the land institutional change to rapid economic growth and structural changes.
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Titus Ebenezer Kwofie, Michael Nii Addy, Alexander Boakye Marful, Clinton Aigbavboa, Samuel Amos-Abanyie, Barbara Simons and Samuel Owusu Afram
Creating green design capability readiness has become an emerging necessity toward increasing sustainable performance. However, the understanding of the green design readiness…
Abstract
Purpose
Creating green design capability readiness has become an emerging necessity toward increasing sustainable performance. However, the understanding of the green design readiness markers for housing delivery is lacking. The purpose of this study is to highlight a green design capability readiness model for affordable housing delivery.
Design/methodology/approach
Through the use of the self-determination theory and the Technology–Organization–Environment framework, a comprehensive review of related literature revealed 23 indicators on motivational, technological, organizational and environmental markers for green design practices capability readiness for affordable housing delivery. Adopting a deductive design, a questionnaire was developed from these markers for a survey on practitioners with knowledge and experience in green design, sustainability and housing supply chain through purposive and snowballing sampling. Mean score analysis and fuzzy synthetic evaluation were subsequently used to develop the capability readiness model.
Findings
This study affirmed the markers and revealed the top indicators in each of the markers. The markers subsequently accounted for 28%, 29%, 17.7% and 25.3% of green design capability readiness for affordable housing delivery. Accordingly, technological and motivational markers had the greatest contributions to green design readiness for affordable housing followed by environmental marker and organizational being the least.
Practical implications
The findings of this study will contribute to developing the right motivations, technological capability and regulatory factors for green design practices to optimize the capability readiness for affordable housing delivery in Ghana.
Originality/value
The model serves as a valuable resource that could be used to objectively align actions and gauge readiness for green design practices toward sustainability performance improvement in affordable housing delivery. It could also aid in benchmarking the readiness potential of future regulations, policies and motivations for green design practices, concepts and technologies for housing delivery.
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Michael Addy, Emmanuel Adinyira, James Cofie Danku and Florence Dadzoe
Developing countries in sub-Saharan Africa are faced with significant challenges as the economies continue to emerge. There is a huge infrastructural demand and various efforts to…
Abstract
Purpose
Developing countries in sub-Saharan Africa are faced with significant challenges as the economies continue to emerge. There is a huge infrastructural demand and various efforts to step up supply. Whilst stepping up the supply, the environmental concerns of these supplies require a lot of attention. With the need to reduce the environmental impact of buildings whilst promoting a green infrastructure, various studies have explored the obstacles to green building technology adoption. This study explores the impediments to the development of the green building market in sub-Saharan Africa.
Design/methodology/approach
Using building consultants as the unit of analysis, this study explores the impediments using a structured survey questionnaire. The study area is Ghana, an emerging country in sub-Saharan Africa.
Findings
Key impediments to the development of the market is lack of awareness, lack of education and lack of fiscal incentives. The analysis shows that all the variables identified are significant in impeding the growth of the market. The results suggest that within the domain of developing countries, environmental issues may not be of immediate concern as economic issues take centre stage. For sustainability of the environment, it is unequivocal that dissemination of knowledge to key stakeholders be done.
Practical implications
Academic institutions and professional bodies have a pivotal role to play in raising awareness of green buildings. Governmental support such as various structures should be put in place to build up the local capacity of firms not only to compete with foreign counterparts but also to ensure innovative delivery of green buildings.
Originality/value
The paper presents contextual realities on the green market restrictions within developing countries in sub-Saharan Africa through a deeper understanding of market barriers and recommends pathways for stakeholders.