
Zhaocai LiuNational Renewable Energy Laboratory | NREL
Zhaocai Liu
Doctor of Philosophy
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27
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Publications
Publications (27)
Studies on the electric bus system planning problem have typically focused exclusively on either the deployment of charging infrastructure or the scheduling of charging events; few have examined the impact of charging facility deployment on charging activities. Considering the interdependence of system design and operational strategies, this study...
Most of the existing traffic simulation packages require significant calibration work to be able to reflect reality. To evaluate special operations including emerging technologies, a microscopic simulation that tracks detailed interactions of all the elements of the traffic systems is usually needed. This type of simulation is usually computational...
Due to the advantage of low emissions, electric buses are an appealing option for public bus systems. However, the driving range restriction and long charging time requirement of electric bus systems limit their development in practice. Wireless power transfer (WPT) is able to charge buses en route and makes electric bus systems more flexible. We c...
As electric vehicles (EVs) become more prevalent, there is growing concern regarding their impact on transportation and power networks. Using vehicle-to-grid (V2G) technology, EVs can operate as additional energy storage sources that make the power grid more efficient and reliable. With their onboard battery, EVs can relocate energy supply spatiall...
Although autonomous vehicle (AV) technology is expected to bring dramatic societal, environmental, and economic benefits, the high vehicle cost might slow the adoption of AVs. This paper explores an infrastructure-enabled autonomous driving system, which is a promising remedy to the high cost of AVs. Specifically, the system combines vehicles and i...
Electromobility in public bus systems is growing rapidly and experiencing a fundamental transformation in their infrastructure and operations. The dilemma of limited driving range and charging time of battery electric buses (BEBs) hinders their adoption. A novel approach to address BEB limitations is to utilize dynamic wireless charging (DWC) techn...
The objective of this research is to reduce energy consumption from intra airport shuttle operations by optimizing routes and schedules, without compromising on passenger travel experience. To achieve this objective, we propose an optimization model that generates optimal airport shuttle routes for a given set of constraints and a discrete-event si...
The development of electromobility along with recent dynamic wireless power transfer technology offers the potential to improve the carbon footprint of public transportation while offering quality services. Existing models for electric bus scheduling cannot adequately capture the dependence among electric bus (EB) battery size, dynamic wireless cha...
Automated Electric Transportation (AET) is an innovative concept that aims to integrate energy, vehicle, highway, and communication infrastructures. It provides an electrified transportation system to support in-motion energy transfer through wireless charging of inductive coupling in the highway. A considerable body of previous research has sought...
Battery electric buses (BEBs) are rapidly being embraced by public transit agencies because of their environmental and economic benefits. To address the problems of limited driving range and time-consuming charging for BEBs, manufacturers have developed rapid on-route charging technology that utilizes typical layovers at terminals to charge buses i...
The use of electric bus fleets has become a topical issue in recent years. This paper aims to analyze strategic bus fleet scheduling and dynamic wireless charging (DWC) planning problems based on data obtained from the transportation center at Binghamton University. More precisely, we have developed a mixed-integer mathematical model to simultaneou...
Emerging autonomous vehicle (AV) technology is expected to bring dramatic societal, environmental, and economic benefits. To promote the realization of the potential benefits of AV technology, this dissertation aims at investigating the modeling and optimization of network infrastructure modification and enhancement planning for autonomous vehicles...
Employing vehicle communication and automated control technologies, autonomous vehicles (AVs) can safely drive closer together than human-driven vehicles (HVs), thereby potentially improving traffic efficiency. Separation between AV and HV traffic through the deployment of dedicated AV lanes is foreseen as an effective method of amplifying the bene...
Employing vehicle communication and automated control technologies, autonomous vehicles (AVs) can safely drive closer together than human-driven vehicles (HVs), thereby potentially improving traffic efficiency. Separation between AV and HV traffic through the deployment of dedicated AV lanes is foreseen as an effective method of amplifying the bene...
Battery electric buses (BEBs) are considered as a promising alternative option for transit vehicles to alleviate the growing environmental problems in urban areas. As a result of the fast charging technology, BEBs are able to provide uninterrupted service without carrying a large battery, which makes them even more attractive. However, fast chargin...
Battery electric buses (BEBs) are increasingly being embraced by transit agencies as an energy-efficient and emission-free alternative to bus fleets. However, due to the limitations of battery technology, BEBs suffer from limited driving range, great battery cost, and time-consuming charging processes. On-route fast charging technology is gaining p...
In recent years, bike share programs have become more popular as they contribute to the move toward sustainable mobility
in cities. Electric bike sharing, however, remains in the early stages of development. In contrast to traditional bikes, electric
bicycles (e-bikes) provide an extra boost via an electric pedal-assist motor, thereby making it muc...
Inspired by the rapid development of charging-while-driving (CWD) technology, plans are ongoing in government agencies worldwide for the development of electrified road freight transportation systems through the deployment of dynamic charging lanes. This en route method for the charging of plug-in hybrid electric trucks is expected to supplement th...
Battery-powered electric buses are gaining popularity as an energy-efficient and emission-free alternative for bus fleets. However, battery electric buses continue to struggle with concerns related to their limited driving range and time-consuming recharging processes. Fast-charging technology, which utilizes dwelling time at bus stops or terminals...
Diesel engine buses still comprise the majority of the bus fleet in the United States even with the problem of diesel exhaust and greenhouse gas emissions. Electric buses, which generate no emissions, provide a promising green alternative for bus fleets. However, electric buses have suffered from their limited travel range and time-consuming rechar...
Highway assets, including traffic signs and signals, light poles, guardrails, and culverts, are essential components of transportation networks. They guide, warn, and protect drivers and regulate traffic. To manage and maintain the regular operation of the highway system, state departments of transportation (DOTs) need reliable and up-to-date infor...