Browsing by Author "Perera, KPH"

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item: Conference-Full-text
Assessment of the optimum dimensions for cobble-type paving blocks using finite element modeling
(IEEE, 2022-07) Kumarage, NR; Jayasinghe, C; Perera, KPH; Kariyawasam, KKGKD; Herath, S; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
A numerical model was developed to investigate the deflection of permeable interlocking concrete blocks. In this study, the acceptance of paving blocks with extensive plan areas was tested. ABAQUS finite element modeling software which is commercially available was used and a static, linear perturbation analysis was carried out. Three alternative block dimensions were determined according to the guidelines provided in ASTM C936 and were modeled. Mesh sensitivity analysis was carried out on each alternative to identify the optimum global element size for each model. Although all three tested models resulted in vertical deformations less than the threshold, the results indicated a positive association between the exposed plan area and the vertical deformation. Finally, it can be concluded as the SLS 1425 recommended paving block dimensions resulted in the most favorable results.
item: Conference-Abstract
Methodology to determine the optimum logistics cost cluster size of multiple facility and server system
(Department of Civil Engineering, University of Moratuwa., 2010) Perera, KPH; Bandara, JMSJ; Pasindu, HR
Majority of suppliers of material required for construction are concentrated in to a particular area to handle their facilities due to the location of existing customers, existing supplying capacity and the locations of their key requirements such as raw material suppliers or sites. The market demand for a particular facility can be exceeded due to the existing demand and due to the growth of facility consumers. So the competition of the market can also be increased. This will encourage the forming of new facilities or plants and also increasing the supplying capacity of existing facilities or plants. With time facility providers can be scattered over a large area with continuous growth of the facility consumers and there is a need to determine the optimum location for new facilities. This type of problems is usually handled by using clustering method to improve the convenience and the efficiency of operation. The usual practice is to consider the geographic basis or arbitrarily based on suppliers and consumers. When there are interactions among the clustered facilities and/or between the facilities and a central server, the cost of transport & logistics operations would be a significant component that affects the efficiency of the system. The problem of locating regional facilities and allocating customers to optimize the cost of transportation covers the core topics of optimums logistic cost cluster model. This paper describes a mathematical model that can be used to determine the optimum location and cluster size for a given facility. This model can be applied in to transportation requirements which based on direct shipment network type such as construction sites of contractor, distribution network of retail stores and serves etc. Transportation problem theories and center of gravity methods were used to develop the model. The cost of transportation was assumed to be proportionate to the distances between the origin and destination. This was later relaxed by using an individual time factor which user can define according to the average speed of the particular road. Operation requirements also introduced to enhance the model accuracy and efficiency such as the concrete delivery time of concrete transportation etc.
item: Thesis-Abstract
Optimum logistic cost cluster size of multiple facilities and server systems
(2016-05-02) Perera, KPH; Bandara, JMSJ
Demand for a particular facility can be exceeded due to the continuous growth of consumers. Therefore the existing competition can also be increased. This will boost the forming of new facilities providers and also increase supplying capacity of existing facilities providers. The location of new facilities and the distribution pattern will be important which causes the system efficiency and the cost of the final product. Identification of the facility locations were usually done by considering the geographic positions or sometimes randomly based on locations of suppliers and consumers. When there are interactions among the different facilities and/or between the facilities and a central server, this practice may become inefficient and the transportation cost may also become higher than the optimum. The problem of locating facilities provider and allocating consumers to optimize the transportation cost covers the core topics of this research. This report describes the formulation of a mathematical model according to the facility requirement. This model can be applied in to transportation requirements based on direct shipment network and/or milk run networks with centralized distribution system. Transportation problem and center of gravity methods were used to develop the proposed methodology. Model initiate with the center of gravity model with relevant operational factors to locate initial plant location for basic goods movement patterns according to the existing demand points. Then the model was executed to next step to expand the system with more facility locations using both single index transportation model and center of gravity model. The final model was capable to work with several types of facilities which were more advanced using multi-index transportation problem and center of gravity model. The transportation cost was assumed to be proportionate to the road distances between the origin and destination which was relaxed by using an individual factor to accommodate the optimum location of facility center within the cluster. Operation requirements such as the concrete delivery time of concrete transportation etc. also introduced to enhance the model practicality.