Wavelet Thresholding for Image Noise Removal

No Abstrac

Causal Analysis at Extreme Quantiles with Application to London Traffic Flow Data

Transport engineers employ various interventions to enhance traffic-network performance. Recent emphasises on cycling as a sustainable travel mode aims to reduce traffic congestion. Quantifying the impacts of Cycle Superhighways is complicated due to the non-random assignment of such an intervention over the transport network and heavy-tailed distribution of traffic flow. Treatment effects on asymmetric and the heavy-tailed distributions are better reflected at extreme tails rather than at averages or intermediate quantiles. In such situations, standard methods for estimating quantile treatment effects at the extremes can provide misleading inference due to the high variability of estimates. In this work, we propose a novel method to estimate the treatment effect at extreme tails incorporating heavy-tailed feature in the outcome distribution. Simulation results show the superiority of the proposed method over existing estimators for quantile causal effects at extremes. The analysis of London transport data utilising the proposed method indicates that the traffic flow increased substantially after the Cycle Superhighway came into operation. The findings can assist government agencies in effective decision making to avoid high consequence events and improve network performance.Comment: arXiv admin note: text overlap with arXiv:2003.0899

RF Energy Harvester-based Wake-up Receiver

Wake-up receivers (WuRxs) can improve the life- time of a wireless sensor network by reducing energy consump- tion from undesirable idle listening. The amplitude level of the incoming RF signal is used by a WuRx to generate an interrupt and wake up the radio of a sleeping sensor node. Existing passive WuRx designs are generally based on RFID tags that incur high cost and complexity. Thus, there is a need for cost-effective and low-complexity WuRxs suited for both long-range and directed wake-ups. In this work, we present a WuRx design using an RF energy harvesting circuit (RFHC). Experimental results show that our RFHC-based WuRx can provide a wake-up range sensitivity around 4 cm/mW at low transmit RF powers ( < 20 mW), which scales to a long wake-up range at high powers. Our design also obtains accurate selective wake-ups. We finally present simulation-based studies for optimizing the design of RFHCs that enhance decoding efficiency with improved rise and fall times