Resilience of Wireless Ad Hoc Federated Learning against Model Poisoning Attacks

Wireless ad hoc federated learning (WAFL) is a fully decentralized collaborative machine learning framework organized by opportunistically encountered mobile nodes. Compared to conventional federated learning, WAFL performs model training by weakly synchronizing the model parameters with others, and this shows great resilience to a poisoned model injected by an attacker. In this paper, we provide our theoretical analysis of the WAFL's resilience against model poisoning attacks, by formulating the force balance between the poisoned model and the legitimate model. According to our experiments, we confirmed that the nodes directly encountered the attacker has been somehow compromised to the poisoned model but other nodes have shown great resilience. More importantly, after the attacker has left the network, all the nodes have finally found stronger model parameters combined with the poisoned model. Most of the attack-experienced cases achieved higher accuracy than the no-attack-experienced cases.Comment: 10 pages, 7 figures, to be published in IEEE International Conference on Trust, Privacy and Security in Intelligent Systems, and Applications 202

Preoperative perihilar cholangiocarcinoma assessment using virtual endoscopic imaging magnetic resonance cholangioscopy

Background and study aims Preoperative assessment of the superficial ductal spread (SDS) of perihilar cholangiocarcinoma (PCCA) is important for determining its resectability. A virtual endoscopic imaging method, magnetic resonance cholangioscopy (MRCS), wherein a three-dimensional image is created from magnetic resonance imaging (MRI) data, can evaluate all aspects of arbitrary bile ducts. Patients and methods Overall, 15 patients with PCCA who underwent preoperative MRI were enrolled. All patients underwent surgical treatment. Results MRCS could be performed based on preoperative MRI data in all patients. MRCS could not be used in one patient due to debris in the obstructed bile duct. The remaining 14 patients (93 %) were diagnosed with obstructed bile duct or irregular surface of the bile duct, signifying tumor invasion. The accuracy rate of diagnosing the SDS was 93 % (14/15). Seven patients underwent preoperative peroral cholangioscopy; the scope could not pass through the tumor in three patients. In these three patients, MRCS was able to be use dtoevaluate the obstructed side of the bile duct and faciliated accurate diagnosis of SDS. Conclusions MRCS can be used to noninvasively evaluate the bile duct in all directions. This novel method makes it easy to create virtual images and can be useful for diagnosing the preoperative SDS of PCCA

Development of a restroom cleaning system for convenience stores

Toilet cleaning is an unhygienic task, and automation of this task is required, particularly in convenience stores. In this study, we propose a toilet cleaning system consisting of a toilet bowl for reducing urine scattering, a toilet bowl top cleaning mechanism, a toilet bowl lifting mechanism, and a toilet floor cleaning robot. The toilet bowl of the proposed system is a combination of the shapes of a typical toilet bowl and a urinal. It effectively reduces splashing when a human urinates in a standing position. At the beginning, the toilet bowl lifting mechanism lifts the toilet bowl to prevent the restroom contamination in advance, and the toilet bowl top cleaning mechanism and floor cleaning robot clean the toilet bowl and floor surface, respectively. The effectiveness of the proposed system was verified in ten experiments using simulated urine and garbage (three pieces of toilet paper, one toilet paper core, and one paper cup). The system was able to collect garbage in all experiments. Each cleaning task required approximately 17 s, and the average removal rate of simulated urine was 97.8%.</p