Browsing by Author "Ranjan, Priya"
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Item Delay, elasticity, and stability trade-offs in rate control(2003) Ranjan, Priya; Abed, Eyad H.; La, Richard J.; ISR; CSHCNWe adopt the optimization framework for rate allocation problem proposed by Kelly and characterize the stability condition with arbitrary communication delay. We demonstrate that there is a fundamental trade-off between the price elasticity of demand of users and responsiveness of the resources through a choice of price function as well as between the system stability and resource utilization.Item Earth Mover’s Distance-Based Tool for Rapid Screening of Cervical Cancer Using Cervigrams(MDPI, 2022-05-06) Shrivastav, Kumar Dron; Arambam, Priyadarshini; Batra, Shelly; Bhatia, Vandana; Singh, Harpreet; Jaggi, Vinita Kumar; Ranjan, Priya; Abed, Eyad H.; Janardhanan, RajivCervical cancer is a major public health challenge that can be cured with early diagnosis and timely treatment. This challenge formed the rationale behind our design and development of an intelligent and robust image analysis and diagnostic tool/scale, namely “OM—The OncoMeter”, for which we used R (version-3.6.3) and Linux (Ubuntu-20.04) to tag and triage patients in order of their disease severity. The socio-demographic profiles and cervigrams of 398 patients evaluated at OPDs of Batra Hospital & Medical Research Centre, New Delhi, India, and Delhi State Cancer Institute (East), New Delhi, India, were acquired during the course of this study. Tested on 398 India-specific women’s cervigrams, the scale yielded significant achievements, with 80.15% accuracy, a sensitivity of 84.79%, and a specificity of 66.66%. The statistical analysis of sociodemographic profiles showed significant associations of age, education, annual income, occupation, and menstrual health with the health of the cervix, where a p-value less than (<) 0.05 was considered statistically significant. The deployment of cervical cancer screening tools such as “OM—The OncoMeter” in live clinical settings of resource-limited healthcare infrastructure will facilitate early diagnosis in a non-invasive manner, leading to a timely clinical intervention for infected patients upon detection even during primary healthcare (PHC).Item Global stability conditions for rate control with arbitrary communication delays(2003) La, Richard J.; Ranjan, Priya; Abed, Eyad H.; ISR; CSHCNWe adopt the optimization framework for the rate allocation problem proposed by Kelly and investigate the stability of the system with arbitrary communication delays between network elements. It is shown that there is a natural underlying discrete time system whose stability is directly related to the stability of the given system. We first present general stability conditions of the system with arbitrary delays, and then apply these results to establish the stability of the system with a family of popular utility and resource price functions. The exponential stability of the system with the given utility and resource price functions is established. We also investigate discretized models that better approximate the packet level dynamics of the system and show that similar stability conditions can be obtained. Numerical examples are provided to validate our analyses.Item Nonlinear Instabilities in TCP-RED(2001) Ranjan, Priya; Abed, Eyad H.; Abed, Eyad H.; ISRThis work introduces a discrete time model for a simplified TCP network with RED control. It is argued that by sampling the state space at certain instants, the dynamics of the system can be described explicitly as a discrete time feedback control system. This system is used to analyze the operating point of TCP-RED and its stability with respect to various controller and system parameters. With the help of bifurcation diagrams, it is numerically shown that non-trivial (not due to the discontinuity in the system or the control law) instabilities in the system are possible due to the presence of a strong nonlinearity in the characteristics of TCP throughput of a sender as a function of drop probability at the gateway. Some of the bifurcations observed in the system are the period-doubling sequence and border collisions leading to a change in the system periodicity and chaos. Analytical techniques are provided to help in the understanding of this kind of anomalous behavior. An explicit stability condition in terms of different parameters is given.Item Stability of rate control system with time-varying communication delays(2004) La, Richard J.; Ranjan, Priya; ISR; CSHCNWe adopt the optimization framework for the rate allocation problem proposed by Kelly and investigate the stability of the system with arbitrary communication delays between network elements with time-varying queue dynamics. We first present the conditions for the existence of a solution of the system. Second, we establish the conditions for the system stability with arbitrary delays for a family of popular utility and price functions, and then extend the results to more general utility and price functions. We demonstrate that the stability of such a system can be studied by considering a discrete time system derived from a simpler homogeneous delay case where all users have the same fixed delay. Numerical examples are provided to validate our analyses.Item Trade-offs in rate control with communication delay(2003) Ranjan, Priya; La, Richard J.; Abed, Eyad H.; ISRWe adopt the optimization framework for rate allocation problem proposed by Kelly and characterize the stability condition with an arbitrary communication delay in the case of single resource. We demonstrate the existence of a fundamental trade-off between users price elasticity of demand and the responsiveness of resource through a choice of price function as well as between system stability and resource utilization. We investigate the effects of non-responsive traffic on system stability and show that the presence of non-responsive traffic enhances the stability of system. We also investigate the system behavior after the system loses its stability.