D RAVINDRAN - Academia.edu (original) (raw)

Papers by D RAVINDRAN

Research paper thumbnail of A hybridisation of metaheuristics for flow shop scheduling

International Journal of Advanced Manufacturing Technology, 2004

The present paper deals with the formation of an optimal sequence of flow shop scheduling (FSS) f... more The present paper deals with the formation of an optimal sequence of flow shop scheduling (FSS) for efficient operation. The primary concern of FSS is to obtain the optimal sequence, which minimises the idle time, tardiness, makespan, etc. Among these, the criteria of minimising the makespan plays a vital part. Thus, in this paper, the sequencing of the FSS for minimising the makespan is addressed. An effective hybrid has been formed with the metaheuristics, namely an ant system and a genetic algorithm (GA). A number of illustrative examples with different combinations of machines and jobs have been solved using the proposed hybrid method.

Research paper thumbnail of Flow shop scheduling with multiple objectiveof minimizing makespan and total flow time

International Journal of Advanced Manufacturing Technology, 2005

This paper deals with the multicriterion approach to flow shop scheduling [FSS] problems by consi... more This paper deals with the multicriterion approach to flow shop scheduling [FSS] problems by considering makespan time and total flow time. The primary concern of flow shop scheduling is to obtain the best sequence, which minimizes the makespan, flow time, idle time, tardiness, etc. In this work, makespan and total flow time of the jobs are considered for minimization. Three heuristic algorithms namely HAMC1, HAMC2 and HAMC3 have been proposed in this paper. The effectiveness of the heuristics has been analyzed using the problems generated by Taillard [16]. The results of the problems are compared with the solution procedures proposed by Rajendran [15]. The new hybrid algorithms are developed by taking the seed sequences yielded by a method proposed by Rajendran [14] in his work to minimize flow time and improving it using search algorithm. The hybrid algorithm gives better results.

Research paper thumbnail of A simple heuristic for linear sequencing of machines in layout design

International Journal of Production Research, 2011

This paper presents a simple heuristic to determine a common linear machine sequence for multiple... more This paper presents a simple heuristic to determine a common linear machine sequence for multiple products with different operation sequences and a limited number of duplicate machine types available for the job. The heuristic is based on minimisation of the total flow distance travelled by a product on the linear machine sequence. It is assumed that the flows of products are allowed only in the forward direction, either in-sequence or by-pass. It is also assumed that backtrack movements are not allowed. The effectiveness of the proposed heuristic is demonstrated through the solutions of two typical layout design problems taken from the literature. Subsequently, a number of additional problems are solved and their results are compared with the results applying existing methods. The results indicate that the proposed method can be an effective tool in solving layout design problems.

Research paper thumbnail of Intermittency Patterns in Proton-Nucleus Interactions at High Energy

Modern Physics Letters A, 1993

A study of intermittency in hadron-nucleus and the comparison with nucleus-nucleus interactions i... more A study of intermittency in hadron-nucleus and the comparison with nucleus-nucleus interactions is presented. The power law behavior of the factorial moments and the variation of intermittency index with the center-of-mass energy are shown. Results favor the formation of quark-gluon plasma in preference to a cascade mechanism.

Research paper thumbnail of Mechanical properties of randomly oriented short Sansevieria cylindrica fibre/polyester composites

Materials & Design, 2011

The tensile, flexural and impact properties of randomly oriented short Sansevieria cylindrica fib... more The tensile, flexural and impact properties of randomly oriented short Sansevieria cylindrica fibre/polyester (SCFP) composites are described for the first time in this work. Composites were fabricated using raw S. cylindrica fibres (SCFs) with varying fibre lengths and weight percents of fibre. When the length of the SCFs was increased, the tensile, flexural and impact properties of the composite were increased up to a 30-mm fibre length, and then a curtailment in properties occurred for higher fibre length composites. SCFP composites showed a regular trend of an increase in properties with fibre weight percent until 40% and afterwards a decrease in properties for composites with greater fibre weight percent. Tensile tests revealed that the tensile strength was about 76 MPa, the Young's modulus was 1.1 GPa and the elongation at break was between 7% and 8.3%. The flexural strength and modulus were estimated to be around 84 MPa and 3 GPa, respectively. Impact tests exhibited a strength of approximately 9.5 J/cm 2 . The analysis of the tensile, flexural and impact properties of short SCFP composites displayed a critical fibre length and optimum fibre weight percent of 30 mm and 40%, respectively. Scanning electron microscope (SEM) studies were carried out to evaluate the fibre/matrix interactions. The experimental tensile strengths were compared with the theoretical predictions and found to be in good agreement with Hirsch's model. An X-ray diffraction (XRD) analysis of the composites exposed the presence of cellulose IV with a crystallinity index of 60% and crystallite size of 68 nm.

Research paper thumbnail of Microstructural, physico-chemical and mechanical characterisation of Sansevieria cylindrica fibres – An exploratory investigation

Materials & Design, 2011

The microstructural, physical, chemical and mechanical properties of Sansevieria cylindrica fibre... more The microstructural, physical, chemical and mechanical properties of Sansevieria cylindrica fibres are described for the first time in this work. A microstructural analysis of S. cylindrica leaves showed the presence of structural fibres and arch fibres. Polarised light microscopy and scanning electron microscopy of these fibres revealed a hierarchical cell structure that consisted of a primary wall, a secondary wall, a fibre lumen and middle lamellae. The cross-sectional area and porosity fraction of the fibre were estimated to be approximately 0.0245 mm 2 and 37%, respectively. The fibre density and fineness were approximately 0.915 ± 0.005 g/cm 3 and 9 Tex, respectively. An X-ray diffraction and Fourier transform infrared analysis of the fibres showed the presence of cellulose I b with a crystallinity index of 60%. Tensile tests showed that the corrected Young's modulus was approximately 7 GPa, the tensile strength was 658 MPa, and the total elongation was between 10% and 12%.

Research paper thumbnail of STRATEGIC-MANAGEMENT-notes einstein college 2

Research paper thumbnail of A hybridisation of metaheuristics for flow shop scheduling

International Journal of Advanced Manufacturing Technology, 2004

The present paper deals with the formation of an optimal sequence of flow shop scheduling (FSS) f... more The present paper deals with the formation of an optimal sequence of flow shop scheduling (FSS) for efficient operation. The primary concern of FSS is to obtain the optimal sequence, which minimises the idle time, tardiness, makespan, etc. Among these, the criteria of minimising the makespan plays a vital part. Thus, in this paper, the sequencing of the FSS for minimising the makespan is addressed. An effective hybrid has been formed with the metaheuristics, namely an ant system and a genetic algorithm (GA). A number of illustrative examples with different combinations of machines and jobs have been solved using the proposed hybrid method.

Research paper thumbnail of Flow shop scheduling with multiple objectiveof minimizing makespan and total flow time

International Journal of Advanced Manufacturing Technology, 2005

This paper deals with the multicriterion approach to flow shop scheduling [FSS] problems by consi... more This paper deals with the multicriterion approach to flow shop scheduling [FSS] problems by considering makespan time and total flow time. The primary concern of flow shop scheduling is to obtain the best sequence, which minimizes the makespan, flow time, idle time, tardiness, etc. In this work, makespan and total flow time of the jobs are considered for minimization. Three heuristic algorithms namely HAMC1, HAMC2 and HAMC3 have been proposed in this paper. The effectiveness of the heuristics has been analyzed using the problems generated by Taillard [16]. The results of the problems are compared with the solution procedures proposed by Rajendran [15]. The new hybrid algorithms are developed by taking the seed sequences yielded by a method proposed by Rajendran [14] in his work to minimize flow time and improving it using search algorithm. The hybrid algorithm gives better results.

Research paper thumbnail of A simple heuristic for linear sequencing of machines in layout design

International Journal of Production Research, 2011

This paper presents a simple heuristic to determine a common linear machine sequence for multiple... more This paper presents a simple heuristic to determine a common linear machine sequence for multiple products with different operation sequences and a limited number of duplicate machine types available for the job. The heuristic is based on minimisation of the total flow distance travelled by a product on the linear machine sequence. It is assumed that the flows of products are allowed only in the forward direction, either in-sequence or by-pass. It is also assumed that backtrack movements are not allowed. The effectiveness of the proposed heuristic is demonstrated through the solutions of two typical layout design problems taken from the literature. Subsequently, a number of additional problems are solved and their results are compared with the results applying existing methods. The results indicate that the proposed method can be an effective tool in solving layout design problems.

Research paper thumbnail of Intermittency Patterns in Proton-Nucleus Interactions at High Energy

Modern Physics Letters A, 1993

A study of intermittency in hadron-nucleus and the comparison with nucleus-nucleus interactions i... more A study of intermittency in hadron-nucleus and the comparison with nucleus-nucleus interactions is presented. The power law behavior of the factorial moments and the variation of intermittency index with the center-of-mass energy are shown. Results favor the formation of quark-gluon plasma in preference to a cascade mechanism.

Research paper thumbnail of Mechanical properties of randomly oriented short Sansevieria cylindrica fibre/polyester composites

Materials & Design, 2011

The tensile, flexural and impact properties of randomly oriented short Sansevieria cylindrica fib... more The tensile, flexural and impact properties of randomly oriented short Sansevieria cylindrica fibre/polyester (SCFP) composites are described for the first time in this work. Composites were fabricated using raw S. cylindrica fibres (SCFs) with varying fibre lengths and weight percents of fibre. When the length of the SCFs was increased, the tensile, flexural and impact properties of the composite were increased up to a 30-mm fibre length, and then a curtailment in properties occurred for higher fibre length composites. SCFP composites showed a regular trend of an increase in properties with fibre weight percent until 40% and afterwards a decrease in properties for composites with greater fibre weight percent. Tensile tests revealed that the tensile strength was about 76 MPa, the Young's modulus was 1.1 GPa and the elongation at break was between 7% and 8.3%. The flexural strength and modulus were estimated to be around 84 MPa and 3 GPa, respectively. Impact tests exhibited a strength of approximately 9.5 J/cm 2 . The analysis of the tensile, flexural and impact properties of short SCFP composites displayed a critical fibre length and optimum fibre weight percent of 30 mm and 40%, respectively. Scanning electron microscope (SEM) studies were carried out to evaluate the fibre/matrix interactions. The experimental tensile strengths were compared with the theoretical predictions and found to be in good agreement with Hirsch's model. An X-ray diffraction (XRD) analysis of the composites exposed the presence of cellulose IV with a crystallinity index of 60% and crystallite size of 68 nm.

Research paper thumbnail of Microstructural, physico-chemical and mechanical characterisation of Sansevieria cylindrica fibres – An exploratory investigation

Materials & Design, 2011

The microstructural, physical, chemical and mechanical properties of Sansevieria cylindrica fibre... more The microstructural, physical, chemical and mechanical properties of Sansevieria cylindrica fibres are described for the first time in this work. A microstructural analysis of S. cylindrica leaves showed the presence of structural fibres and arch fibres. Polarised light microscopy and scanning electron microscopy of these fibres revealed a hierarchical cell structure that consisted of a primary wall, a secondary wall, a fibre lumen and middle lamellae. The cross-sectional area and porosity fraction of the fibre were estimated to be approximately 0.0245 mm 2 and 37%, respectively. The fibre density and fineness were approximately 0.915 ± 0.005 g/cm 3 and 9 Tex, respectively. An X-ray diffraction and Fourier transform infrared analysis of the fibres showed the presence of cellulose I b with a crystallinity index of 60%. Tensile tests showed that the corrected Young's modulus was approximately 7 GPa, the tensile strength was 658 MPa, and the total elongation was between 10% and 12%.

Research paper thumbnail of STRATEGIC-MANAGEMENT-notes einstein college 2