Fleet replacement decisions under demand and fuel price uncertainties

2018 ◽  
Vol 60 ◽  
pp. 153-173 ◽  
Author(s):  
Shiyuan Zheng ◽  
Shun Chen
Author(s):  
Anne Liret ◽  
Amir H. Ansaripoor ◽  
Fernando S. Oliveira

1976 ◽  
Vol 190 (1) ◽  
pp. 71-80 ◽  
Author(s):  
A. K. S. Jardine ◽  
T. S. Goldrick ◽  
J. Stender

SYNOPSIS The paper reports a study of the determination of an optimal replacement policy for transport fleet vehicles in the 7/8 ton load carrying capacity. Comments are made about the limitations of the constant economic life approach to replacement decisions. The concept of an Annual Maintenance Cost Limit approach is suggested and used to set replacement decisions for a fleet of 150 similar vehicles.


Author(s):  
N.S. Mustafa ◽  
N.H.A. Ngadiman ◽  
M.A. Abas ◽  
M.Y. Noordin

Fuel price crisis has caused people to demand a car that is having a low fuel consumption without compromising the engine performance. Designing a naturally aspirated engine which can enhance engine performance and fuel efficiency requires optimisation processes on air intake system components. Hence, this study intends to carry out the optimisation process on the air intake system and airbox geometry. The parameters that have high influence on the design of an airbox geometry was determined by using AVL Boost software which simulated the automobile engine. The optimisation of the parameters was done by using Design Expert which adopted the Box-Behnken analysis technique. The result that was obtained from the study are optimised diameter of inlet/snorkel, volume of airbox, diameter of throttle body and length of intake runner are 81.07 mm, 1.04 L, 44.63 mm and 425 mm, respectively. By using these parameters values, the maximum engine performance and minimum fuel consumption are 93.3732 Nm and 21.3695×10-4 kg/s, respectively. This study has fully accomplished its aim to determine the significant parameters that influenced the performance of airbox and optimised the parameters so that a high engine performance and fuel efficiency can be produced. The success of this study can contribute to a better design of an airbox.


2018 ◽  
Vol 4 (2) ◽  
Author(s):  
Soni S. Wirawan dkk

Biodiesel is a viable substitute for petroleum-based diesel fuel. Its advantages are improved lubricity, higher cetane number and cleaner emission. Biodiesel and its blends with petroleum-based diesel fuel can be used in diesel engines without any signifi cant modifi cations to the engines. Data from the numerous research reports and test programs showed that as the percent of biodiesel in blends increases, emission of hydrocarbons (HC), carbon monoxide (CO), and particulate matter (PM) all decrease, but the amount of oxides of nitrogen (NOx) and fuel consumption is tend to increase. The most signifi cant hurdle for broader commercialization of biodiesel is its cost. In current fuel price policy in Indonesia (especially fuel for transportation), the higher percent of biodiesel in blend will increase the price of blends fuel. The objective of this study is to assess the optimum blends of biodiesel with petroleum-based diesel fuel from the technically and economically consideration. The study result recommends that 20% biodiesel blend with 80% petroleum-based diesel fuel (B20) is the optimum blend for unmodifi ed diesel engine uses.Keywords: biodiesel, emission, optimum, blend


2019 ◽  
Vol 68 (6) ◽  
pp. 411-419 ◽  
Author(s):  
Gamze Güngör-Demirci ◽  
Juneseok Lee ◽  
Jonathan Keck ◽  
Stephen J. Harrison ◽  
Geoffrey Bates

Abstract Groundwater wells are critical drinking water infrastructure elements that widely support basic system supply needs while also providing supply reliability, better water quality (in some cases), and comparatively lower operational costs. Well rehabilitation and replacement are thus an area where water utilities could benefit from rational decision support frameworks and quantitative tools that enable them to better navigate the complex trade-off relationship(s) that exist among a variety of environmental quality, public health, financial, regulatory, organizational, and technological dimensions. Consistent with these considerations, a business risk-based prioritization tool was developed for this study that augments/extends California Water Service (Cal Water)'s well rehabilitation and the replacement decision-making process. For this derivation, a business risk exposure methodology is combined with an analytical hierarchy process (AHP), with the AHP being utilized to determine the weights of the factors involved in the likelihood of failure and the consequence of failure calculation. It is expected that the new tool will assist in optimizing inspection and action plans and identify the wells requiring attention and/or additional work for water utilities.


Energy ◽  
2021 ◽  
Vol 225 ◽  
pp. 120236
Author(s):  
Claudiu Tiberiu Albulescu ◽  
Mihai Ioan Mutascu
Keyword(s):  

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