On the Empty Miles of Ride-Sourcing Services: Theory, Observation and Countermeasures

The proliferation of smartphones in recent years has catalyzed the rapid growth of ride-sourcing services such as Uber, Lyft, and Didi Chuxing. Such on-demand e-hailing services significantly reduce the meeting frictions between drivers and riders and provide the platform with unprecedented flexibility and challenges in system management. A big issue that arises with service expansion is the empty miles produced by ride-sourcing vehicles. To overcome the physical and temporal frictions that separate drivers from customers and effectively reposition themselves towards desired destinations, ride-sourcing vehicles generate a significant number of vacant trips. These empty miles traveled result in inefficient use of the available fleet and increase traffic demand, posing substantial impacts on system operations. To tackle the issues, my dissertation is dedicated to deepening our understanding of the formation and the externalities of empty miles, and then proposing countermeasures to bolster system performance. There are two essential and interdependent contributors to empty miles generated by ride-sourcing vehicles: cruising in search of customers and deadheading to pick them up, which are markedly dictated by forces from riders, drivers, the platform, and policies imposed by regulators. In this dissertation, we structure our study of this complex process along three primary axes, respectively centered on the strategies of a platform, the behaviors of drivers, and the concerns of government agencies. In each axis, theoretical models are established to help understand the underlying physics and identify the trade-offs and potential issues that drive behind the empty miles. Massive data from Didi Chuxing, a dominant ride-sourcing company in China, are leveraged to evidence the presence of matters discussed in reality. Countermeasures are then investigated to strengthen management upon the empty miles, balance the interests of different stakeholders, and improve the system performance. Although this dissertation scopes out ride-sourcing services, the models, analyses, and solutions can be readily adapted to address related issues in other types of shared-use mobility services.PHDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163209/1/xzt_1.pd

An Integer L-shaped Method for Dynamic Order Dispatching in Autonomous Last-Mile Delivery with Demand Uncertainty

Given the potential to significantly reduce the cost and time in last-mile delivery, autonomous delivery solutions via delivery robots or unmanned aerial vehicles have received increasing attention. This paper studies the dynamic order dispatching problem in an autonomous last-mile delivery system with intrinsic demand uncertainty. We consider a rolling order-fulfilment context and formulate a two-stage stochastic programming to take into account both existing unfulfilled orders and future incoming requests to minimize the total expected delays in package delivery. The considered uncertainty includes the stochastic arrival of delivery requests, their types, locations/delivery distances, and associated penalties for late delivery. Due to the constrained service capacity, the size of the problem grows exponentially as the number of simulated scenarios increases. In this study, we propose a modified integer L-shaped method, which (i) significantly reduces the number of nodes in the branching tree, and (ii) simplifies the computation of optimality cuts. The computational results show that these two modifications improve the average running time by roughly 10 times and 1,000 times compared to the non-customized L-shaped method and the classic branch-and-bound method, respectively. The linearly growing computational speed in response to the number of scenarios enables it as a viable solution for large-sized problems in reality

Stabilization computation for a kind of uncertain switched systems using non-fragile sliding mode observer method

A non-fragile sliding mode control problem will be investigated in this article. The problem focuses on a kind of uncertain switched singular time-delay systems in which the state is not available. First, according to the designed non-fragile observer, we will construct an integral-type sliding surface, in which the estimated unmeasured state is used. Second, we synthesize a sliding mode controller. The reachability of the specified sliding surface could be proved by this sliding mode controller in a finite time. Moreover, linear matrix inequality conditions will be developed to check the exponential admissibility of the sliding mode dynamics. After that, the gain matrices designed will be given along with it. Finally, some numerical result will be provided, and the result can be used to prove the effectiveness of the method

El patrimonio arqueológico del distrito Tambobamba - Apurímac y sus perspectivas de gestión

Se focaliza en el poblado de Tambobamba, en la cual analiza la situación actual del patrimonio arqueológico, evaluando el estado de protección del patrimonio arqueológico y los lineamientos existentes para implementar la gestión del Patrimonio Arqueológico del poblado de Tambobamba. Se debe indicar, además, que es el punto de partida para futuros trabajos que engloben a todo el distrito. Para el efecto se recurrió a la investigación documental y de campo, mediante el contacto con la realidad estudiada. Los resultados reflejan escasa participación de las autoridades locales en la gestión y manejo de los vestigios arqueológicos ubicados en su territorio; además de una escasa coordinación entre los diversos niveles de gobierno en lo que respecta a la problemática arqueológica. Por lo anterior se considera que es importante realizar un Plan de Gestión con objetivos a corto, mediano y largo plazo para las acciones de implementación, protección y conservación del patrimonio cultural y arqueológico de la zona; asimismo, promover la participación y la coordinación de todos los comprometidos con la protección del patrimonio, autoridades, instituciones del estado, organismos que promueven el turismo (agencias) y la población de la zona.Tesi

A new solution for destruction of PCDD/Fs by a catalytic filter system at waste incinerators

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are emitted from high temperature combustion processes such as municipal waste incinerators, hazardous waste incinerators, medical waste incinerators, and secondary metal processing plants. Due to their extreme toxicity, stringent regulations on PCDD/Fs emissions have been in effect around the world since the early 1990s. W. L. Gore & Associates, Inc. developed a catalytic filter system in 1997 that can effectively remove and destroy PCDD/Fs in the industrial flue gases. The REMEDIATM Catalytic Filter System has been installed in various industrial facilities around the world. The dioxin emission measurements in these plants achieve more than 98% PCDD/Fs removal efficiencies and reach the European standard. In this paper, three case studies will be presented on the performance of the REMEDIA Catalytic Filter System at municipal, medical, and hazardous waste incinerators. Three cases in the paper demonstrate the efficiency and results

Vibration Analysis of Bilayered Graphene Sheets for Building Materials in Thermal Environments Based on the Element-Free Method

Graphene sheets are widely applied due to their unique and highly valuable properties, such as energy conservation materials in buildings. In this paper, we investigate the vibration behavior of double layer graphene sheets (DLGSs) in thermal environments which helps probe into the mechanism of energy conservation of graphene sheets in building materials. The nonlocal elastic theory and classical plate theory (CLPT) are used to derive the governing equations. The element-free method is employed to analyze the vibration behaviors of DLGSs embedded in an elastic medium. The accuracy of the solutions in this study is demonstrated by comparison with published results in the literature. Furthermore, a number of numerical results are presented to investigate the effects of various parameters (boundary conditions, nonlocal parameter, aspect ratio, side length, elastic foundation parameter, and temperature) on the frequency of DLGSs