在位置隐私保护中,差分隐私保护机制通过随机函数对真实位置加噪,从而保护真实位置信息.然而在隐私预算分配问题上往往易造成资源浪费以及隐私保护效率低下.针对此问题,本文在已有研究的基础之上提出一种基于概率相似性度量的差分隐私算...在位置隐私保护中,差分隐私保护机制通过随机函数对真实位置加噪,从而保护真实位置信息.然而在隐私预算分配问题上往往易造成资源浪费以及隐私保护效率低下.针对此问题,本文在已有研究的基础之上提出一种基于概率相似性度量的差分隐私算法DPBO.首先,使用加权有向图来收集获取历史位置信息;然后通过范围度量找出历史位置点与真实轨迹中每个位置点R所对应的相似位置点集SET,对SET与R进行一对多(One To Many, OTM)概率相似性度量,得出每个R点的位置敏感度ΔG;最后根据不同ΔG,为真实轨迹中R分配相应隐私预算,添加Laplace噪声.通过实验,证明了该方案具有数据可用性和可行性.展开更多
The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio o...The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio of input mixture and ignition position on the engine performance of a dual-cylinder FPEG was investigated,and their sensitivity was analyzed in this paper.The operating compression ratio of the system is susceptible to changes in excess air ratio and ignition position.At the same time,it decreases from 15.8 to 6.6 when excess air ratio increases from 0.85 to 1.15,but it increases from 6.1 to 13.3 as ignition position increases from 15 mm to 20 mm.The operating frequency and indicated power are more sensitive to changes in excess air ratio than ignition position.But it is the opposite for the indicated thermal efficiency and friction loss.Excess air ratio and ignition position have a quite similar influence on heat transfer.Therefore,from the perspective of system operation and performance,it is preferable to keep excess air coefficient slightly below 1.0.In contrast,when selecting ignition position,it is of great importance to comprehensively consider the risk of structural damage caused by the increase in the compression ratio and in-cylinder gas pressure.展开更多
文摘在位置隐私保护中,差分隐私保护机制通过随机函数对真实位置加噪,从而保护真实位置信息.然而在隐私预算分配问题上往往易造成资源浪费以及隐私保护效率低下.针对此问题,本文在已有研究的基础之上提出一种基于概率相似性度量的差分隐私算法DPBO.首先,使用加权有向图来收集获取历史位置信息;然后通过范围度量找出历史位置点与真实轨迹中每个位置点R所对应的相似位置点集SET,对SET与R进行一对多(One To Many, OTM)概率相似性度量,得出每个R点的位置敏感度ΔG;最后根据不同ΔG,为真实轨迹中R分配相应隐私预算,添加Laplace噪声.通过实验,证明了该方案具有数据可用性和可行性.
基金Projects(51675043,52005038)supported by the National Natural Science Foundation of China。
文摘The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio of input mixture and ignition position on the engine performance of a dual-cylinder FPEG was investigated,and their sensitivity was analyzed in this paper.The operating compression ratio of the system is susceptible to changes in excess air ratio and ignition position.At the same time,it decreases from 15.8 to 6.6 when excess air ratio increases from 0.85 to 1.15,but it increases from 6.1 to 13.3 as ignition position increases from 15 mm to 20 mm.The operating frequency and indicated power are more sensitive to changes in excess air ratio than ignition position.But it is the opposite for the indicated thermal efficiency and friction loss.Excess air ratio and ignition position have a quite similar influence on heat transfer.Therefore,from the perspective of system operation and performance,it is preferable to keep excess air coefficient slightly below 1.0.In contrast,when selecting ignition position,it is of great importance to comprehensively consider the risk of structural damage caused by the increase in the compression ratio and in-cylinder gas pressure.
