A surrogate model for interference prevention in the limaçon-to-limaçon machines
- Authors: Sultan, Ibrahim
- Date: 2007
- Type: Text , Journal article
- Relation: Engineering Computations (Swansea, Wales) Vol. 24, no. 5 (2007), p. 437-449
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- Description: Purpose - This paper aims to replace the complicated iterative procedure used to prevent interference in limacon-to-limacon machines by a simplified mathematical equation which can be solved by a straightforward substitution of the required clearance value. Design/methodology/approach - The input data to the iterative procedure and the obtained results have been employed in regression models to construct the sought after equation. Searching for a proper form of this equation involved numerical experiments to study the effects of the various model parameters on the system response. Findings - The numerical experiments conducted proved to be an effective model construction technique, and the regression model proposed has been found extremely accurate in the specified parameter space. Research limitations/implications - The proposed equation is applicable within the parameter range chosen for the study. This range is the one often used for industrial applications. Should the parameters selected for a specific design fall outside the specified range, the proposed model structure may have to be varied to maintain a desirable level of accuracy. Practical implications - The interference study is a part of the iterative procedure employed to design the dimensions of the limaçon-to-limaçon machine. This iterative procedure searches for the proper design amongst hundreds of various possible solutions. The results of this paper will ensure a much faster convergence for the design procedure, since the interference study will be eliminated from the iterative section of the analysis. Originality/value - The paper offers a valid and accurate model that can be efficiently used for the intended purpose. © Emerald Group Publishing Limited.
- Description: C1
- Description: 2003004799
Inverse geometric design for a class of rotary positive displacement machines
- Authors: Sultan, Ibrahim
- Date: 2008
- Type: Text , Journal article
- Relation: Inverse Problems in Science and Engineering Vol. 16, no. 2 (2008), p. 127-139
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- Description: Inverse design techniques in the area of fluid mechanics are normally conducted for continuous flow turbomachines rather than positive displacement devices. However, the work in this article is concerned with a class of rotary positive displacement device referred to as the limaçon-to-limaçon machine. The rotors and housings of these machines are manufactured of limaçon profiles, and are likely to suffer from interference if the rotors are not carefully profiled. Published literature indicates that solutions proposed to tackle the interference problem in these machines will adversely affect their efficiency figures. This notion motivated the work presented in this article, which first introduces the relevant mathematical models of the limaçon-to-limaçon machine and then uses these models to construct an inverse geometric design problem formulation. The proposed model has been coded in a computer program that utilises a Marquardt-Levenberg technique to converge to the required geometric parameters. Case studies are presented at the end of the article to verify the validity of the proposed inverse design model.
- Description: C1
Simplified theodolite calibration for robot metrology
- Authors: Sultan, Ibrahim , Wager, John
- Date: 2002
- Type: Text , Journal article
- Relation: Advanced Robotics Vol. 16, no. 7 (2002), p. 653-671
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- Description: Theodolites represent a well-established three-dimensional-point-measuring technology. However, when used for robot applications they have to be properly calibrated to fulfil the necessary accuracy requirements. The theodolite calibration methods reported in the literature involve the use of costly sophisticated equipment not easily available to most users. Therefore, a new simplified calibration technique is presented based on the use of a graduated precision bar suspended freely to align with the vertical direction. To develop efficient mathematical models, the theodolites will be regarded as 2R open-ended mechanisms with the end-effector axis directed along the line of sight. The proposed models are then coded in a computer program designed to verify the validity of the technique presented. The simulation results will be presented at the end of the paper.
- Description: 2003000163
Optimum positioning of ports in the limaon gas expanders
- Authors: Sultan, Ibrahim , Schaller, Carl
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Engineering for Gas Turbines and Power Vol. 133, no. 10 (2011), p.
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- Description: Positive displacement expanders are quickly gaining popularity in the fields of micropower generation and refrigeration engineering. Unlike turbomachines, expanders can handle two-phase flow applications at low speed and flow rate levels. This paper is concerned with a simple-design positive displacement expander based on the lima̧on of Pascal. The paper offers an insight into the thermodynamic workings of the limaison gas expander and presents a mathematical model to describe the manner in which the port locations affect the expander performance. A stochastic optimization technique is adopted to find the locations, for the expander ports, which produce best expander performance for given chamber dimensions. The operating speed and other parameters will be held constant during the optimization procedure. A case study is offered in this paper to prove the validity of the presented approach, and comments are given on how various operating parameters affect system performance in the limaison design. © 2011 American Society of Mechanical Engineers.