This paper focuses on transits available around the world. AC voltage transits and DC voltage transit are reviewed and compared. Emphasis is given to differences, advantages and disadvantages of voltage supplies and traction types. First, differences between bus rapid transit (BRT), metro, light rail transit (LRT) and light metro are covered, with special attention to statistical of annual passengers per year, an attribute that defines the type of railway transit. Mention is also made to the history of DC and AC overhead wires, other traction preferences for metro transit and highlighted differences between the third rail and fourth rail traction. Malaysian transit systems are then discussed, with special attention to LRT Kelana Jaya line, world"s third DC transit that employs the fourth rail traction. The discussion have produced relevant statistical data that this paper is in part aimed at summarizing and at comparing with what accomplished on the same subject within the third rail traction framework. The increased in LRT Kelana Jaya line annual passengers per year is a proof of success for the fourth rail technology.
Commercial grid-connected rooftop solar PV systems are widely applied worldwide as part of affordable and clean energy initiatives and viable long-term solutions for energy security. This is particularly true in a crowded city where space is a constraint and at the same time, there are unutilized rooftops. With the recently announced Net Energy Metering (NEM) 3.0, commercial buildings in Malaysia can apply up to 75% capacity of the maximum demand (MD), which can be connected to the grid. Apart from reducing electricity bills, the owner can offset energy for 10 years. This paper presents a design analysis with the details of the sizing of a rooftop PV system. The PVsyst software tool is used to estimate the energy produced by a 380 kWp system, and this study provides a financial analysis to evaluate the profitability of the system with a particular interest in commercial buildings under the NEM 3.0 policy, which has resulted in 8.4 years return of investment (ROI). PVsyst is a software used to size the PV system and provides technical, financial, and environmental analysis. This in-depth analysis could provide a useful case study for asset owners in deciding the way forward for sustainable energy production, cost saving, and combating the energy security issue, since Malaysia is blessed with an abundance of sunshine throughout the year.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.