Efficient protocols for heavy hitter identification with local differential privacy

Local differential privacy(LDP),which is a technique that employs unbiased statistical estimations instead of real data,is usually adopted in data collection,as it can protect every user’s privacy and prevent the leakage of sensitive information.The segment pairs method(SPM),multiple-channel method(MCM)and prefix extending method(PEM)are three known LDP protocols for heavy hitter identification as well as the frequency oracle(FO)problem with large domains.However,the low scalability of these three LDP algorithms often limits their application.Specifically,communication and computation strongly affect their efficiency.Moreover,excessive grouping or sharing of privacy budgets makes the results inaccurate.To address the abovementioned problems,this study proposes independent channel(IC)and mixed independent channel(MIC),which are efficient LDP protocols for FO with a large domains.We design a flexible method for splitting a large domain to reduce the number of sub-domains.Further,we employ the false positive rate with interaction to obtain an accurate estimation.Numerical experiments demonstrate that IC outperforms all the existing solutions under the same privacy guarantee while MIC performs well under a small privacy budget with the lowest communication cost.

High-Voltage-Gain DC-DC Converter with Three-Winding Coupled Inductor

A novel DC-DC converter topology that uses a three-winding coupled inductor(TWCI)and a new voltagemultiplication technique is presented for achieving high voltage gain.The proposed converter comprises one boost unit,one passive absorption circuit,and two voltage-multiplier cells.The tertiary winding of the coupled inductor is connected to a capacitor and diode,and this combination acts as a secondary voltage-multiplier cell(SVMC).The SVMC,when combined with two capacitors,the secondary winding of the coupled inductor,a diode,and a switch,forms a primary voltage-multiplier cell,which can achieve a large voltage-conversion ratio that can be adjusted easily.The new voltage-multiplier technique can be used to decrease the number of capacitors and diodes,which improves the transformation efficiency.A prototype circuit with a nominal rating of 300 W is designed to verify the correctness of theoretical analysis.