Hai Wang

Hai Wang
Singapore Management University | smu · School of Compuging and Information Systems

Professor

About

36
Publications
4,874
Reads
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778
Citations
Introduction
Received dual master's in transportation and operations research at MIT, and Ph.D. in operations research from the Sloan School of Management at MIT. Research focuses on methodologies in analytics and optimization, data-driven modeling, and computational machine learning algorithms, and the applications in a broad context of smart city, including mobility and transportation, e-commerce and logistics, and healthcare problems.

Publications

Publications (36)
Article
Recently, some third-party integrators attempt to integrate the ride services offered by multiple independent ride-sourcing platforms. Accordingly, passengers can request ride through the integrators and receive ride service from any one of the ride-sourcing platforms. This novel business model, termed as third-party platform-integration in this wo...
Article
The last-mile problem refers to the provision of travel service from the nearest public transportation node to home or other destination. Last-Mile Transportation Systems (LMTS), which have recently emerged, provide on-demand shared transportation. In this paper, we investigate the fleet sizing and allocation problem for the on-demand LMTS. Specifi...
Article
With increasing container-shipping traffic, congestion at transshipment hub ports happens from time to time incurring longer-than-expected waiting time for vessels and loss of transshipment connections. This situation is even worse for feeder companies, due to their relatively lower berthing priority. It is essential to design the feeder vessel rou...
Article
Ride-sourcing services are increasingly popular because of their ability to accommodate on-demand travel needs. A critical issue faced by ride-sourcing platforms is the supply-demand imbalance, as a result of which drivers may spend substantial time on idle cruising and picking up remote passengers. Some platforms attempt to mitigate the imbalance...
Preprint
The last-mile problem refers to the provision of travel service from the nearest public transportation node to home or other destination. Last-Mile Transportation Systems (LMTS), which have recently emerged, provide on-demand shared transportation. In this paper, we investigate the fleet sizing and allocation problem for the on-demand LMTS. Specifi...
Article
With rapid population growth and increasing demand for urban mobility, metropolitan areas such as Singapore, Tokyo, and Shanghai are increasingly dependent on public transport systems. Various strategies are proposed to improve the service quality and capacity of bus and subway systems. Express trains—i.e., trains that skip certain stations—are com...
Preprint
Full-text available
One of the central issues in (finite horizon) online planning problems is to synthesize the impact of real time decisions on the subsequent states of the system, and the performance in the remaining time horizon (cost-to-go function). A complete resolution often leads to intractable dynamic programming problems. In this paper, we propose a computat...
Article
With the recent rapid growth of technology-enabled mobility services, ride-sourcing platforms, such as Uber and DiDi, have launched commercial on-demand ride-pooling programs that allow drivers to serve more than one passenger request in each ride. Without requiring the prearrangement of trip schedules, these programs match on-demand passenger requ...
Preprint
Full-text available
Recently, some transportation service providers attempt to integrate the ride services offered by multiple independent ride-sourcing platforms, and passengers are able to request ride through such third-party integrators or connectors and receive service from any one of the platforms. This novel business model, termed as third-party platform-integr...
Article
Full-text available
Robotic on-orbit servicing (OOS) is expected to be a key technology and concept for future sustainable space exploration. This paper develops a novel semi-analytical model for OOS system analysis, responding to the growing needs and ongoing trend of robotic OOS. An OOS infrastructure system is considered whose goal is to provide responsive services...
Article
Surge pricing is commonly used in on-demand ridesourcing platforms to dynamically balance demand and supply, although it is controversial and has long stimulated debate regarding its pros and cons. In practice, there is usually a reasonable or legitimate range of prices. However, such a constrained surge-pricing strategy may fail to balance demand...
Preprint
Full-text available
Robotic on-orbit servicing (OOS) is expected to be a key technology and concept for future sustainable space exploration. This paper develops a novel semi-analytical model for OOS system analysis, responding to the growing needs and ongoing trend of robotic OOS. An OOS infrastructure system is considered whose goal is to provide responsive services...
Article
Full-text available
SEPSIS-3 DEFINITION: Sepsis is defined as life-threatening organ dysfunction due to a dysregulated host response to infection. The clinical criteria of sepsis include organ dysfunction, which is defined as an increase of two points or more on the sequential organ failure assessment (SOFA). For patients with infection, an increase of 2 SOFA points y...
Article
With the popularization of ride-sharing services, drivers working as freelancers on ride-sharing platforms can design their schedules flexibly. They make daily decisions regarding whether to participate in work, and if so, how many hours to work. Factors such as hourly income rate affect both the participation decision and working-hour decision, an...
Chapter
Many on-demand service platforms use a fixed payout ratio (i.e., the percentage of the platform’s revenue that is paid to the providers) regardless of the customer demand and the number of participating providers that tend to vary over time. In this chapter, we examine the implications of time-based payout ratios. To do so, we first present a queue...
Article
We study the following multi-period multi-objective online ride-matching problem. A ride-sourcing platform needs to match passengers and drivers in real time without observing future information, considering multiple objectives such as platform revenue, pick-up distance, and service quality. We develop an efficient online matching policy that adapt...
Conference Paper
Full-text available
Effective traffic management can help port operators gain a competitive edge in service level and efficient use of limited resources. One critical aspect of traffic management is gate operations management, ensuring a good customer experience to logistic carriers and considering the impact of congestion in and around the port. In this paper, we des...
Conference Paper
Full-text available
With increasing container-shipping traffic in major transshipment ports, unsynchronized shipping services at hub ports usually lead to loss of transshipment connections, significant vessel port-stay time, and congestion. This calls for the design of feeder vessel services to pick up from and deliver containers to neighboring local ports, and, at th...
Article
The Last-Mile Problem refers to the provision of travel service for passengers from the nearest public transportation node to the final destination. The Last-Mile Transportation System (LMTS), which has recently emerged, provides on-demand shared last-mile transportation service for passengers. We consider an LMTS that consists of two types of pass...
Conference Paper
With rapid population growth and increasing demand for urban mobility, metropolitan areas such as Singapore, Tokyo, and Shanghai are increasingly dependent on public transport systems. Various strategies are proposed to improve the service quality and capacity of bus and subway systems. Express trains-i.e., trains that skip certain stations-are com...
Article
The indeterministic relations between unobservable events and observed outcomes in partially identified models can be characterized by a bipartite graph. Given a probability measure on observed outcomes, the set of feasible probability measures on unobservable events can be defined by a set of linear inequality constraints, according to Artstein's...
Conference Paper
Full-text available
Port capacity is determined by three major infrastructural resources namely, berths, yards and gates. The advertised capacity is constrained by the least of the capacities of the three resources. While a lot of attention has been paid to optimizing berth and yard capacities, not much attention has been given to analyzing the gate capacity. The gate...
Article
The relations between unobserved events and observed outcomes can be characterized by a bipartite graph. We propose an algorithm that explores the structure of the graph to construct the "exact Core Determining Class," i.e., the set of irredudant inequalities. We prove that in general the exact Core Determining Class does not depend on the probabil...
Article
Consider a situation when an on-demand service platform uses earnings-sensitive independent providers with heterogeneous reservation price (for work participation) to serve its wait-time and price sensitive customers with heterogeneous valuation of the service. As such, both the supply and demand are “endogenously” dependent on the price the platfo...
Article
Full-text available
The Last Mile Problem refers to the provision of travel service from the nearest public transportation node to a home or office. Last Mile Transportation Systems (LMTS) are critical extensions to traditional public transit systems. We study the LMTS from three perspectives. The first part of this thesis focuses on the design of a LMTS. We study the...

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