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Search Results: 1 - 10 of 284059 matches for " D.T. Thao "
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Interaction model for predicting bead geometry for Lab Joint in GMA welding process
D.T. Thao,I.S. Kim
Archives of Computational Materials Science and Surface Engineering , 2009,
Abstract: Purpose: The prediction of the optimal bead geometry is an important aspect in robotic welding process. Therefore, the mathematical models that predict and control the bead geometry require to be developed. This paper focuses on investigation of the development of the simple and accuracy interaction model for prediction of bead geometry for lab joint in robotic Gas Metal Arc (GMA) welding process.Design/methodology/approach: The sequent experiment based on full factorial design has been conducted with two levels of five process parameters to obtain bead geometry using a GMA welding process. The analysis of variance (ANOVA) has efficiently been used for identifying the significance of main and interaction effects of process parameters. General linear model and regression analysis has been employed as a guide to achieve the linear, curvilinear and interaction models. The fitting and the prediction of bead geometry given by these models were also carried out. Graphic results display the effects of process parameter and interaction effects on bead geometry.Findings: The fitting and the prediction capabilities of interaction models are reliable than the linear and curlinear models and it was found that welding voltage, arc current, welding speed and 2-way interaction CTWD welding angle have the large significant effects on bead geometry.Research limitations/implications: The these models developed are extended to shielding gas composition, weld joint position, polarity and many other parameters which are not included in this research in order to establish a closed loop feedback control system to minimize possible errors from uncontrolled variations.Practical implications: The developed models apply real-time control for bead geometry in GMA welding process and perform the Design of Experiments (DOE) analysis steps in order to solve optimisation problems in GMA welding process.Originality/value: The interaction factors, welding voltage arc current, CTWD welding angle, also imposes a significant effect on bead geometry. With the experimental data of this study, the interaction models have a more reliable fitting and better predicting than that of linear and curvilinear models.
Predicting Lap-Joint bead geometry in GMA welding process
D.T. Thao,J.W. Jeong,I.S. Kim,J.W.H.J. Kim
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: The prediction of the optimal bead geometry is an important aspect in robotic welding process. Therefore, the mathematical models that predict and control the bead geometry require to be developed. This paper focuses on investigation of the development of the simple and accuracy interaction model for prediction of bead geometry for lap joint in robotic Gas Metal Arc (GMA) welding process.Design/methodology/approach: The sequent experiment based on full factorial design has been conducted with two levels of five process parameters to obtain bead geometry using a GMA welding process. The analysis of variance (ANOVA) has efficiently been used for identifying the significance of main and interaction effects of process parameters. General linear model and regression analysis in SPSS has been employed as a guide to achieve the linear, curvilinear and interaction models. The fitting and the prediction of bead geometry given by these models were also carried out. Graphic results display the effects of process parameter and interaction effects on bead geometry.Findings: The fitting and the prediction capabilities of interaction models are reliable than the linear and curvilinear models. It was found that welding voltage, arc current, welding speed and 2-way interaction CTWD×welding angle have the large significant effects on bead geometry.Practical implications: The model should also cover a wide range of material thicknesses and be applicable for all welding position. For the automatic welding system, the data must be available in the form of mathematical equations.Originality/value: It has been realized that with the use of the developed algorithm, the prediction of optimal bead dimensions becomes much simpler to even a novice user who has no prior knowledge of the robotic GMA welding process and optimization techniques.
Opening the trinity: developing the “open theism” debate
D.T Williams
Acta Theologica , 2005,
Abstract: The reconciliation of the omniscience of God with the free choices of humanity is a problem which has taxed Christian thinkers for centuries. Recently the issue has become prominent with the emergence of support for “open theism”, the belief that free will is such that God cannot know the future, simply because it has not yet happened. This idea has produced considerable opposition largely based on the perceived insecurity with which it leaves Christians, and the feeling that it diminishes God. A further solution to the problem can be based on the concept of God’s kenosis, that God has freely chosen to limit himself, specifically his knowledge. As this is a freely chosen action of God, so not an inherent limitation, and is temporary, it meets the fundamental objections to open theism. At the same time, kenosis was done for the sake of enabling a relationship with God, in which Christians do find ultimate security.
A kenotic response to secularity
D.T. Williams
Koers : Bulletin for Christian Scholarship , 2008, DOI: 10.4102/koers.v73i1.155
Abstract: The church must be concerned to make the correct response to its increasing impotence and marginalisation in Western society due to secularisation. Past reaction has been to accommodate to the changed worldview, even to identify with it. A more appropriate response is to be Christocentric, so as to reflect the action of God himself in the sending of Christ for salvation. This involved his kenosis . In this case the response of the church is its own kenosis. This is also appropriate as secularisation was possible through the kenosis of God. The kenosis of the church is not an acceptance of defeat, but on the contrary, just as the kenosis of Christ, it aims at a positive result, the transformation of society.
Secularisation from kenosis
D.T. Williams
Koers : Bulletin for Christian Scholarship , 2007, DOI: 10.4102/koers.v72i1.194
Abstract: Recent decades have witnessed the acceleration of the process of secularisation, along with related effects in society such as a decline in morals. Christians must wonder why God allows this to happen. The suggestion is that this is a result of God’s selflimitation, kenosis, allowing a process of which He does not approve for the sake of human free will. Kenosis follows as a possible result of a distinction between the divine and the created world, which permits secularisation. This is generally seen as a result of the Renaissance, Reformation and Enlightenment, with effects in industrialisation and urbanisation; all of these can be linked with God’s kenosis. However, secularisation must not be seen as inevitable, but as having been exacerbated by the state of the church. If the result is a refining of the church, it could eventually lead to a resacralising of society.
Kenosis and the nature of the Persons in the Trinity
D.T. Williams
Koers : Bulletin for Christian Scholarship , 2004, DOI: 10.4102/koers.v69i4.320
Abstract: Philippians 2:7 describes the kenosis of Christ, that is Christ’s free choice to limit himself for the sake of human salvation. Although the idea of Christ’s kenosis as an explanation of the incarnation has generated considerable controversy and has largely been rejected in its original form, it is clear that in this process Christ did humble himself. This view is consistent with some contemporary perspectives on God’s self-limitation; in particular as this view provides a justification for human freedom of choice. As kenosis implies a freely chosen action of God, and not an inherent and temporary limitation, kenosis is consistent with an affirmation of God’s sovereignty. This view is particularly true if Christ’s kenosis is seen as a limitation of action and not of his attributes. Such an idea does not present problems concerning the doctrine of the Trinity, specifically regarding the relation between the economic and the immanent nature of the Trinity. The Trinitarian doctrine, on the contrary, indeed complements this idea – specifically the concept of perichoresis (the interrelatedness among the Persons of the Triniy and the relation between the two natures of Christ).
What is life?
D.T. Williams
Koers : Bulletin for Christian Scholarship , 2002, DOI: 10.4102/koers.v67i3.373
Abstract: The question of the nature of life, and therefore of the soul and spirit, has troubled people since time immemorial, especially if they are seen as essentially immaterial. It is suggested that the soul may be understood as the process of life, the inter-relationship between the parts of the body, and that the spirit is the driving force that motivates life. This is then related to the role of God in life, and particularly as the originator of new life in salvation.
The Spirit and secularisation
D.T. Williams
Koers : Bulletin for Christian Scholarship , 2010, DOI: 10.4102/koers.v75i4.109
Abstract: The existence of creation, especially of life, depends on the work of the third Person. In keeping with his nature as holy, the Spirit undergirds creation by providing separation and relatedness. This activity is, however, not of such a kind as to remove the measure of freedom that God gave through his selflimitation, and that is necessary for creation to occur. It is possible for individuals and society as a whole to ignore the Spirit, and for secularisation to occur. The action of the Spirit also underlies the new creation, which results in a distinctive society, the church, which is characterised by separation and relatedness. Through the church, the Spirit seeks to influence society as a whole by example without removing its freedom. To maintain the validity of this example, the Spirit also seeks to develop the church as a holy society, specifically counteracting the factors that produce secularisation in society.
The perfect three: ontology as trinity
D.T. Williams
Koers : Bulletin for Christian Scholarship , 1988, DOI: 10.4102/koers.v53i2.874
Abstract: The Ontological Argument fo r the existence of God is briefly examined with particular reference to its basic premise, the assumption of the perfection of God. Despite some problems with the idea, it is believed that perfection is a valid concept. The thrust of the article is that if a perfect God exists, such perfection requires at least the basic concepts of the doctrine of the Trinity . The author therefore believes th a t the idea of the Trinity is derivable in a rudimentary form without reference to either revelation or to the "vestigia" (the supposed reflection of the Trinity in the creation), but simply from the idea of perfection. Some authors, both medieval and modern are cited in support of the argument.
Time and Strain Response of Repeated Ageing Treatments on Recycled Al-Si-Cu Alloy
D.T. GUNDU
American Journal of Engineering Research , 2013,
Abstract: The objective of this study was to investigate the time response of 3-stage artificial ageing treatments on strength properties of recycled Al-Si-Cu alloy with a view to obtaining useful empirical relationships for predicting required treatment cycles. True compressive stress, micro hardness and strain (%) were evaluated in response to ageing time and repeated ageing. The results of compression and hardness tests showed that alloy hardness and compressive stress increased with ageing time, and that these properties also increased with repeated ageing. The results also showed that alloy strain (%) reduced with ageing time and repeated ageing, indicating increasing strength or strain hardening of the alloy with repeated ageing. Using these results, empirical models of the form n = 0eαt, and n = 0eαN are established for predicting the required ageing time and/or number of ageing treatments to raise the strength (or hardness) of an alloy to desired levels to meet service requirements. The strain response of the alloy is modelled as εn = ε0e αt.
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