Browsing by Subject "Capacity analysis"
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Item Open Access Capacity analysis of a PMR system with DAB downlink(IEEE, 2003) Şengül, Ersin; Can, B.; Akar, Nail; İder, Yusuf Ziya; Köymen, HayrettinSeveral trunked private mobile radio (PMR) systems have been designed over the last decade, most of which have symmetric downlink and uplink channel capacities. These systems may not be spectrally efficient in case of group or broadcast-based voice and data calls, a common feature of PMR systems. We propose a new asymmetric PMR system comprising a wideband OFDM-based downlink and a narrowband uplink, which not only achieves a better spectral efficiency but also can support high bit rate multimedia applications. The system is shown to have high trunking efficiency since all users are assumed to use the pool of channels available in the wideband downlink. In this paper, we study the performance and capacity of a private mobile radio system using a digital audio broadcasting (DAB) downlink. In particular, we study the efficiency of such a system for voice calls using voice activity detection and statistical multiplexing. Moreover, we show that, the efficiency of the system can significantly increase, if the incoming calls, which can not find an available channel, are allowed to wait a certain amount of time before occupying a channel.Item Open Access The impact of discharge decisions on health care quality(Institute for Operations Research and the Management Sciences (INFORMS), 1998) Berk, E.; Moinzadeh, K.In this paper, we present a normative study that describes the impact of discharging decisions in the face of resource shortages. We develop a model that represents the dynamics of a health care unit. Then, to capture the essence of discharge decisions, we consider discharge policies that incorporate both the occupancy level of the unit and the status of patients measured by their stage of recovery and the time they have spent in that stage. We believe that our model can be used as an aid to physicians and administrators to better assess discharge and/or capacity decisions. In addition, we investigate the impact of discharge decisions on the measures that represent the quality of care at a facility such as average hospital stays, system accessibility, and average complication risk of discharged patients. Our findings illustrate that inclusion of early discharge option improves system accessibility significantly and does not jeopardize care equity among patients. Furthermore, introduction of early discharge option has more pronounced effects on increasing care unit capacity than addition of open beds with no early discharges.Item Open Access Two countermeasure strategies to mitigate random disruptions in capacitated systems(2010) Bakır, N. O.; Savachkin, A.; Uribe-Sanchez, A.We examine a capacitated system exposed to random stepwise capacity disruptions with exponentially distributed interarrival times and uniformly distributed magnitudes. We explore two countermeasure policies for a risk-neutral decision maker who seeks to maximize the long-run average reward. A one-phase policy considers implementation of countermeasures throughout the entirety of a disruption cycle. The results of this analysis form a basis for a two-phase model which implements countermeasures during only a fraction of a disruption cycle. We present an extensive numerical analysis as well as a sensitivity study on the fluctuations of some system parameter values.