2 resultados para communication policy
em DRUM (Digital Repository at the University of Maryland)
Resumo:
Facing the exigencies of Emancipation, a South in ruins, and ongoing violence, between 1862 and 1872 the United States Congress debated the role education would play in the postbellum polity. Positing schooling as a panacea for the nation’s problems, a determiner of individual worth, and a way of ameliorating state and federal tensions, congressional leaders envisioned education as a way of reshaping American political life. In pursuit of this vision, many policymakers advocated national school agencies and assertive interventions into state educational systems. Interrogating the meaning of “education” for congressional leaders, this study examines the role of this ambiguous concept in negotiating the contradictions of federal and state identity, projecting visions of social change, evaluating civic preparedness, and enabling broader debates over the nation’s future. Examining legislative debates over the Reconstruction Acts, Freedmen’s Bureau, Bureau of Education, and two bills for national education reform in the early 1870s, this project examines how disparate educational visions of Republicans and Democrats collided and mutated amid the vicissitudes of public policy argument. Engaging rhetorical concepts of temporality, disposition, and political judgment, it examines the allure and limitations of education policy rhetoric, and how this rhetoric shifted amid the difficult process of coming to policy agreements in a tumultuous era. In a broader historical sense, this project considers the role of Reconstruction Era congressional rhetoric in shaping the long-term development of contemporary Americans’ “educational imaginary,” the tacit, often unarticulated assumptions about schooling that inflect how contemporary Americans engage in political life, civic judgment, and social reform. Treating the analysis of public policy debate as a way to gain insights into transitions in American political life, the study considers how Reconstruction Era debate converged upon certain common agreements, and obfuscated significant fault lines, that persist in contemporary arguments.
Resumo:
In energy harvesting communications, users transmit messages using energy harvested from nature. In such systems, transmission policies of the users need to be carefully designed according to the energy arrival profiles. When the energy management policies are optimized, the resulting performance of the system depends only on the energy arrival profiles. In this dissertation, we introduce and analyze the notion of energy cooperation in energy harvesting communications where users can share a portion of their harvested energy with the other users via wireless energy transfer. This energy cooperation enables us to control and optimize the energy arrivals at users to the extent possible. In the classical setting of cooperation, users help each other in the transmission of their data by exploiting the broadcast nature of wireless communications and the resulting overheard information. In contrast to the usual notion of cooperation, which is at the signal level, energy cooperation we introduce here is at the battery energy level. In a multi-user setting, energy may be abundant in one user in which case the loss incurred by transferring it to another user may be less than the gain it yields for the other user. It is this cooperation that we explore in this dissertation for several multi-user scenarios, where energy can be transferred from one user to another through a separate wireless energy transfer unit. We first consider the offline optimal energy management problem for several basic multi-user network structures with energy harvesting transmitters and one-way wireless energy transfer. In energy harvesting transmitters, energy arrivals in time impose energy causality constraints on the transmission policies of the users. In the presence of wireless energy transfer, energy causality constraints take a new form: energy can flow in time from the past to the future for each user, and from one user to the other at each time. This requires a careful joint management of energy flow in two separate dimensions, and different management policies are required depending on how users share the common wireless medium and interact over it. In this context, we analyze several basic multi-user energy harvesting network structures with wireless energy transfer. To capture the main trade-offs and insights that arise due to wireless energy transfer, we focus our attention on simple two- and three-user communication systems, such as the relay channel, multiple access channel and the two-way channel. Next, we focus on the delay minimization problem for networks. We consider a general network topology of energy harvesting and energy cooperating nodes. Each node harvests energy from nature and all nodes may share a portion of their harvested energies with neighboring nodes through energy cooperation. We consider the joint data routing and capacity assignment problem for this setting under fixed data and energy routing topologies. We determine the joint routing of energy and data in a general multi-user scenario with data and energy transfer. Next, we consider the cooperative energy harvesting diamond channel, where the source and two relays harvest energy from nature and the physical layer is modeled as a concatenation of a broadcast and a multiple access channel. Since the broadcast channel is degraded, one of the relays has the message of the other relay. Therefore, the multiple access channel is an extended multiple access channel with common data. We determine the optimum power and rate allocation policies of the users in order to maximize the end-to-end throughput of this system. Finally, we consider the two-user cooperative multiple access channel with energy harvesting users. The users cooperate at the physical layer (data cooperation) by establishing common messages through overheard signals and then cooperatively sending them. For this channel model, we investigate the effect of intermittent data arrivals to the users. We find the optimal offline transmit power and rate allocation policy that maximize the departure region. When the users can further cooperate at the battery level (energy cooperation), we find the jointly optimal offline transmit power and rate allocation policy together with the energy transfer policy that maximize the departure region.