Universally Near Optimal Online Power Control for Energy Harvesting Nodes

We consider online power control for an energy harvesting system with random i.i.d. energy arrivals and a finite size battery. We propose a simple online power control policy for this channel that requires minimal information regarding the distribution of the energy arrivals and prove that it is universally near-optimal for all parameter values. In particular, the policy depends on the distribution of the energy arrival process only through its mean and it achieves the optimal long-term average throughput of the channel within both constant additive and multiplicative gaps. Existing heuristics for online power control fail to achieve such universal performance. This result also allows us to approximate the long-term average throughput of the system with a simple formula, which sheds some light on the qualitative behavior of the throughput, namely how it depends on the distribution of the energy arrivals and the size of the battery.Comment: the proposed scheme is shown to be optimal both within constant additive and multiplicative gaps; submitted to Journal on Selected Areas in Communications - Series on Green Communications and Networking (Issue 3); revised following reviewers' comment

Does Managerial 'Outsourcing' Reduce Expense Preference Behavior? A Comparison of Adopters and Non-Adopters of Contract-Management in US Hospitals

This paper explores potential realization of gains by hospitals that are managed on a day-to-day basis by external organizations under formal contracts. It draws from the incentives literature, which postulates that managers of firms where ownership is separated from control will employ an input mix that deviates from cost minimization. While this status applies to hospitals generally, we hypothesize that specialized managerial expertise, coupled with the threat of non-renewal, will improve efficiency in hospitals that opt for contract. Secondary data obtained from the AHA Annual Surveys (1991-1998) are applied to examine the distribution of expense preference' parameters for all contract management adopters both pre- and post-adoption. These are contrasted with two control groups of hospitals drawn from the same years using propensity score methods. Results reveal allocative inefficiency among both adoption and control groups but a significantly lower change in the expense preference parameter pre- and post-adoption associated with a staffing. This suggests that changes in incentive contracts are one important strategy hospitals are using to cope with competitive pressures.