Model Development and Simulation for Estimating the Moulding Behaviour of River Sand at Different Clay Contents
Ejovwokode Edward Mukoro,
Binfa Bongfa
Issue:
Volume 10, Issue 5, October 2022
Pages:
90-104
Received:
9 July 2022
Accepted:
15 August 2022
Published:
16 September 2022
DOI:
10.11648/j.ijmea.20221005.11
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Abstract: Foundry operatives have been conducting laboratory tests physically and characterizing silica sand of river bed for moulding purposes with a view to ascertaining their properties. This has made flexibility and speed of decision-making difficult during moulding practice. This study was aimed at developing a model and simulation for estimating the moulding behaviour of river Niger coarse sand at different clay contents. Physical tests were carried out on 90 samples of coarse sand/clay/water composition. Experimental data obtained from the physical tests were used to develop modeling equations. The equations were then used to develop the software for simulation. Statistical tests were used to validate the developed models. The GFN of the coarse sand was 42.42%. Grain distribution indicated a normal curve showing the different sizes of sand that aided sand mould compactability. The trend of the relationship properties and clay content indicated linearity in compactability (38-50), green hardness (55-82), green shear strength (0-160) and shatter index (38-55) while an inverse linearity was observed in permeability (150-125). However, green compression strength which maintained a steady positive relationship from 5-9% clay showed a fluctuating pattern up to 13% clay. The model equations predicted the output close to the experimental results using Silica Sand Mould Properties Determination (SSMPD) software. The software was developed using VISUAL BASIC programming language. It is user friendly and runs on Window computer of at least 1 MB RAM and 3.0 GB free hard disk with information on the installation, running and using the application software. This SSMPD has contributed to rapid determination of coarse sand properties for foundry mould practice.
Abstract: Foundry operatives have been conducting laboratory tests physically and characterizing silica sand of river bed for moulding purposes with a view to ascertaining their properties. This has made flexibility and speed of decision-making difficult during moulding practice. This study was aimed at developing a model and simulation for estimating the mo...
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Sensor Characteristics Attributable to Base Plate Thickness of Piezo-Composite Sensors
Nobuhiro Shimoi,
Kazuhisa Nakasho,
Carlos Cuadra
Issue:
Volume 10, Issue 5, October 2022
Pages:
105-112
Received:
16 August 2022
Accepted:
30 August 2022
Published:
16 September 2022
DOI:
10.11648/j.ijmea.20221005.12
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Abstract: After the huge East Japan Earthquake, many steel structures have been constructed using welded frame welded joints and welded foundation construction. Although steel-frame structures are regarded as earthquake-resistant structures, many steel-frame structures are built using fillet-welded frame-welded joints and welded column bases. These welded joints might have less ability to absorb energy during an earthquake. Therefore, when designing steel structures that use welded joints, it is necessary to consider the seismic resistance of column bases in particular. To confirm the safety of these unstable structures, we propose measurements using piezo-composite sensors. The measurement results suggest long-term evaluation of these structures. As described in this paper, the relation between the sensor output and the thickness of the piezo-composite sensor base plate was found quantitatively using data obtained using a measurement robot (SALLY). Next, after fabricating a piezo-composite sensor that can measure displacement when the deformation angle of the strut is 1/100 or 1/200, we verified it using a mounting test. We conducted a similar experiment using a measurement robot and compared the sensor characteristics. Herein, results obtained using the measurement robot (SALLY) for the relation between the output and displacement of piezo compound sensors is explained. The mounting test of the piezo junction sensor used under the optimum conditions for the robot measurement confirmed that the target displacement measurement can be measured from the sensor output by changing the piezo-composite sensor plate thickness.
Abstract: After the huge East Japan Earthquake, many steel structures have been constructed using welded frame welded joints and welded foundation construction. Although steel-frame structures are regarded as earthquake-resistant structures, many steel-frame structures are built using fillet-welded frame-welded joints and welded column bases. These welded jo...
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A New DEA Cross-Efficiency Method Based on Consensus
Issue:
Volume 10, Issue 5, October 2022
Pages:
113-122
Received:
25 July 2022
Accepted:
22 September 2022
Published:
28 September 2022
DOI:
10.11648/j.ijmea.20221005.13
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Abstract: Data Envelopment Analysis (DEA), as a non-parametric technique for evaluating the relative efficiencies of a set of homogenous decision-making units (DMUs) with multi-inputs and multi-outputs, is widely used in the performance evaluation field. This paper develops a new DEA cross-efficiency method based on consensus (CEC-DEA), which can be more reasonably and effectively in evaluating and ranking decision-making units (DMUs). In our proposed method, we firstly attempt to obtain the unique set of weights for each DMU through a second-objective model which can minimize the total variance between the self-evaluated efficiencies and the peer-evaluated efficiencies. Then, based on the acquired weights, the cross-efficiency scores of all DMUs are calculated. Before the cross-efficiency aggregation, we choose a DMU as the Common Reference Point (CRP) based on which all the cross-efficiency scores are rescaled to be comparable for the aggregation. In the aggregation stage, we define the Evaluation Consensus Degrees (ECDs) of all DMUs, which are used as the weights to aggregate the cross-efficiency scores through the weighted geometric mean method. Comprehensively, the proposed CEC-DEA method is developed to increase the rationality and acceptability of the evaluations for all DMUs. Finally, the a numerical example is illustrated to prove the effectiveness of the proposed method.
Abstract: Data Envelopment Analysis (DEA), as a non-parametric technique for evaluating the relative efficiencies of a set of homogenous decision-making units (DMUs) with multi-inputs and multi-outputs, is widely used in the performance evaluation field. This paper develops a new DEA cross-efficiency method based on consensus (CEC-DEA), which can be more rea...
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