A Linear Programming Approach to Optimization of Ship Design and Construction Phases

2008 ◽  
Vol 24 (01) ◽  
pp. 1-6
Author(s):  
Howard Moyst ◽  
Biman Das
Keyword(s):  
Linear Programming ◽  
Labor Cost ◽  
Ship Design ◽  
Programming Approach ◽  
Actual Case ◽  
Study Results ◽  
Lp Model ◽  
Degree Of Overlap ◽  
Design And Construction

Labor cost savings can be obtained by considering the effect of design rework on the degree of overlap of the ship design and construction phases. Based on data from a shipbuilding case study, a linear programming (LP) model was developed to investigate the optimum overlap of the design and construction phases. Two scenarios were modeled. The case study's start-up period, which involved design and the construction of four ships, and a hypothetical small batch program to determine the degree of overlap and total hours required for a new shipbuilding program. In each scenario, the LP model found the optimum overlap period for design and construction and the associated total hours. In the first scenario, the analysis demonstrates that by reducing the amount of overlap between the design and construction phases, a reduction in construction direct labor hours can be achieved while obtaining the overall duration and scheduled completion times. In the second case, the analysis recommends a zero overlap policy between the design and construction phases to minimize total hours while achieving the overall schedule duration. When compared with the actual case study results, the zero overlap policy estimates an $8 million saving. The analysis supports the policy to complete design activities with construction-dependency relationships before starting construction.

scholarly journals Incorporating the Credit Constraint in a Linear Programming Model: A Case Study of a Rural Farmer in Zimbabwe

2013 ◽  
Vol 1 (2) ◽  
pp. 245-250
Author(s):  
Felix Majeke ◽  
Michael Ticharwa Mubvuma ◽  
Kasirayi Makaza
Keyword(s):  
Linear Programming ◽  
Programming Model ◽  
Linear Programming Model ◽  
Working Capital ◽  
Credit Constraint ◽  
Important Constraint ◽  
Model Solutions ◽  
Lp Model

The available working capital required to finance purchase of inputs on a farm like seeds for instance, can be an important constraint on a farm. Some working capital may be available from the farm family‘s savings. The farmer may have an option for increasing his working capital by borrowing. In this study, a linear programming model was developed in order to determine the optimal crop combination for a rural farmer. The linear programming model incorporated the credit constraint. The objective was to maximize income. Crops considered were maize, soya beans, cotton and tobacco. Tobacco gained acreage by 291.33%.Soya beans and cotton lost acreage completely. Maize lost acreage by 73.5%. The optimal income increased from $9,877.00 to $22,774.60. The optimal income showed an improvement of 130.58% compared to the farmer‘s existing plan. The results show that LP model solutions are worthy implementing because they increase income.

An Integer Programming Approach to Optimize the Plantation in Order to Reduce Global Warming

2012 ◽  
Vol 548 ◽  
pp. 767-771 ◽  
Author(s):  
C. Vanlisuta ◽  
Suksan Prombanpong
Keyword(s):  
Mathematical Model ◽  
Linear Programming ◽  
Objective Function ◽  
Programming Model ◽  
Programming Approach ◽  
Profit Function ◽  
Carbon Credit ◽  
Integer Linear Programming Model ◽  
The Mathematical Model

The objective of this paper is to determine the number and species of trees to be planted in order to maximize a profit through an integer linear programming model. The mathematical model is developed in terms of the profit function. This objective function is therefore, a difference between carbon credit revenue and costs of plantation. The economical plants are only considered in the model. Consequently, fourteen different tree species are to be investigated. The objective function is subjected to several constraints i.e. planting area, carbon sequestration and so on. The planting envelope of each tree is assigned 4 by 4 meters. In this paper, the Eastern part of Thailand is considered the case study. It is found that three kinds of plants, Copper pod, Cananga, and Bullet wood are suitable for planting. A number of trees to be planted in 1600 square meter are twenty, thirty, and fifty plants respectively. The profit earned is of 12,112 $ per year in the next fifth year.

scholarly journals Agricultural resources management through a linear programming approach: A case study on productivity optimization of crop-livestock farming integration

2018 ◽  
Vol 22 (1) ◽  
pp. 27
Author(s):  
Hemanatha P. W. Jayasuriya ◽  
Romy Das
Keyword(s):  
Linear Programming ◽  
Case Study Research ◽  
Farming System ◽  
Herd Size ◽  
Programming Approach ◽  
Land Resources ◽  
Livestock Farming ◽  
Agricultural Resources ◽  
Nutrient Recycle

The crop-livestock integrated farming system practiced in most developing countries depends to a greater extent on the ecosystem as a whole. The importance of animals as an agent of nutrient recycle, sources of rural energy in terms of draft power and fuel as well as major contributor of the farm economy, has resulted into increased population of ruminant stock in these regions creating threats to the sustainability and productivity of land resources. This case-study research attempted to formulate optimum herd size compatible to different resource holding farm categories within the sub watershed in mid hills region of Nepal. The research was conducted by classified data collection in Nepal and analysis using Linear Programming (LP) techniques. The LP analysis revealed that the farmers of large, medium and small categories of farms can optimize their livestock holding with combination of 3 Livestock Units (LU) buffaloes and 4 LU goats, 2 LU buffaloes and 4 LU goats and 1 LU buffaloes and 4.4 LU goats with maximum return to the farm family without exerting pressure on the fragile natural resources.

Proven Benefits of Advanced Shipbuilding Technology: Actual Case Studies of Recent Comparative Construction Programs

1988 ◽  
Vol 4 (03) ◽  
pp. 147-154
Author(s):  
A. B. Nierenberg ◽  
S. G. Caronna
Keyword(s):  
Quality Assurance ◽  
Ship Design ◽  
Organizational Changes ◽  
Actual Case ◽  
Ship Construction ◽  
Construction Methods ◽  
Depth Study ◽  
Comparative Construction ◽  
Commercial Environment ◽  
Design And Construction

This paper documents the transformations that have occurred and the benefits that have been realized as a result of the implementation of advanced shipbuilding technology at Avondale in the period from 1976 through 1986. The vehicle for this evaluation is the in-depth study and comparison of two pairs of similar construction programs. Each pair is characterized by one program being performed by traditional shipbuilding design and construction methods and its comparative vessel program being developed utilizing advanced ship design and construction methodology at Avondale. The comparison of these ship construction programs includes discussions of the transformations which have occurred in each of the major shipbuilding disciplines, including engineering, production planning, material, manufacturing, quality assurance and facilities, as well as an in-depth quantification of the benefits derived from the overall shipbuilding process. The evolution that occurred in this ten-year period includes not only the changes in methods and procedures solely for improved shipbuilding productivity, but also the extensive material, procedural and organizational changes required to perform under full U.S. Navy contract requirements as compared to the pure commercial environment which existed at the shipyard at the start of the period.

A Methodology and Case Study to Assess SCOR-Make Agility Measures Under Uncertainties

2020 ◽  
Vol 11 (3) ◽  
pp. 1-16
Author(s):  
Piyanee Akkawuttiwanich ◽  
Pisal Yenradee
Keyword(s):  
Linear Programming ◽  
Predictive Models ◽  
Bottled Water ◽  
Easy Task ◽  
Lp Model ◽  
Level 1

An assessment of agility is not an easy task since agility has been differently defined in literature, and it is not convenient to measure by experiment in practice. The objective of this paper is to propose a methodology to assess the agility performance under uncertainties based on level 1 of SCOR-Make process metric including the upside make flexibility (AG1.1), upside make adaptability (AG1.2), and downsize make adaptability (AG1.3). The proposed methodology consists of predictive models, which are a deterministic linear programming (LP) model and LP model with uncertainties, and algorithms to assess the agility measures. A case study of a bottled-water factory is conducted to demonstrate the application of the proposed methodology. The case study shows that the proposed methodology can effectively determine the agility measures. It can also be adapted to answer other agility related practical questions that are different from the SCOR definition.

scholarly journals MILP for Optimizing Water Allocation and Reservoir Location: A Case Study for the Machángara River Basin, Ecuador

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 1011 ◽  
Author(s):  
Jaime Veintimilla-Reyes ◽  
Annelies De Meyer ◽  
Dirk Cattrysse ◽  
Eduardo Tacuri ◽  
Pablo Vanegas ◽  
...  
Keyword(s):  
Linear Programming ◽  
River Basin ◽  
Network Flow ◽  
Water Allocation ◽  
Mixed Integer ◽  
Spatially Distributed ◽  
Lp Model ◽  
Milp Model ◽  
Network Flow Optimization

The allocation of water flowing through a river-with-reservoirs system to optimally meet spatially distributed and temporally variable demands can be conceived as a network flow optimization (NFO) problem and addressed by linear programming (LP). In this paper, we present an extension of the strategic NFO-LP model of our previous model to a mixed integer linear programming (MILP) model to simultaneously optimize the allocation of water and the location of one or more new reservoirs; the objective function to minimize only includes two components (floods and water demand), whereas the extended LP-model described in this paper, establishes boundaries for each node (reservoir and river segments) and can be considered closer to the reality. In the MILP model, each node is called a “candidate reservoir” and corresponds to a binary variable (zero or one) within the model with a predefined capacity. The applicability of the MILP model is illustrated for the Machángara river basin in the Ecuadorian Andes. The MILP shows that for this basin the water-energy-food nexus can be mitigated by adding one or more reservoirs.

Factors Affecting Ship Design and Construction Lead Time and Cost

2005 ◽  
Vol 21 (03) ◽  
pp. 186-194
Author(s):  
Howard Moyst ◽  
Biman Das
Keyword(s):  
Design Process ◽  
Lead Time ◽  
Ship Design ◽  
Start Time ◽  
Design Quality ◽  
Improve Design ◽  
Design Changes ◽  
The Impact ◽  
Design And Construction

This paper reviews a ship design and construction case study in the context of the published literature on the design process and its impact on construction. The objective was to explore the factors that impact design and construction lead time and cost. Design and construction managers constantly experience pressure to accelerate the construction start time in an environment characteristic of frequent design changes and rework. Often the construction of the first ships of a series will aggressively overlap the design phase. This investigation assessed a case study that illustrated that as the degree of overlap between design and construction increases, design changes increased ship construction costs and duration. This negates the advantage of trying to reduce lead time by overlapping phases. Before strategies of overlapping are utilized, shipbuilders need to better understand the details of the design process and its integration with other functions to improve design quality and reduce the impact of design changes on manufacturing and construction. It is recommended that when overlapping strategies are considered, design changes and their impact on construction be factored into the decision. A better strategy would be to eliminate design quality issues and design and construction rework.

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