Practical Differentially Private and Byzantine-resilient Federated Learning

Privacy and Byzantine resilience are two indispensable requirements for a federated learning (FL) system. Although there have been extensive studies on privacy and Byzantine security in their own track, solutions that consider both remain sparse. This is due to difficulties in reconciling privacy-preserving and Byzantine-resilient algorithms. In this work, we propose a solution to such a two-fold issue. We use our version of differentially private stochastic gradient descent (DP-SGD) algorithm to preserve privacy and then apply our Byzantine-resilient algorithms. We note that while existing works follow this general approach, an in-depth analysis on the interplay between DP and Byzantine resilience has been ignored, leading to unsatisfactory performance. Specifically, for the random noise introduced by DP, previous works strive to reduce its impact on the Byzantine aggregation. In contrast, we leverage the random noise to construct an aggregation that effectively rejects many existing Byzantine attacks. We provide both theoretical proof and empirical experiments to show our protocol is effective: retaining high accuracy while preserving the DP guarantee and Byzantine resilience. Compared with the previous work, our protocol 1) achieves significantly higher accuracy even in a high privacy regime; 2) works well even when up to 90% of distributive workers are Byzantine

What is the impact of recent reforms on English teaching in vocational education in Ningbo?

This thesis investigates the impact of recent curriculum reforms on English teachers and teaching in secondary vocational education in a Chinese city. It uses case study methodology to examine the impact of the reforms on teachers’ professional identities and the factors that support or challenge their professional development. The study draws upon Lave and Wenger’s theories about communities of practice to explain the pressures the teachers are under. The thesis contributes to a better understanding of how vocational English teachers’ professional identity is being reorganised within a transforming educational context, and it raises a demand for better comprehension of the relationship between individual and context in the implementation of educational reform in China

Lonicera flos and Curcuma longa L. extracts improve growth performance, antioxidant capacity and immune response in broiler chickens

Alternatives to antibiotics are urgently needed to maintain broiler growth and health. The present study was conducted to evaluate the effects of Lonicera flos and Curcuma longa L. extracts (LCE) as antibiotic substitutes on growth performance, antioxidant capacity and immune response in broilers. A total of 480 one-day-old female broilers (WOD168) were allocated to 3 treatments with 5 replicates of 32 birds for 35 days. The 3 treatments were: an antibiotic-free basal diet (control, CON), CON +50 mg/kg spectinomycin hydrochloride and 25 mg/kg lincomycin hydrochloride (ANT), CON +500 mg/kg LCE (LCE). During the entire experimental period, supplementation of ANT and LCE increased (p < 0.01) average daily gain (ADG) and decreased (p < 0.05) feed conversion ratio (FCR), thereby resulting in greater final body weight (BW) compared with CON. Dietary LCE supplementation increased (p < 0.05) serum (glutathione peroxidase) GSH-Px, (superoxide dismutase) SOD and total antioxidant capacity (T-AOC) activities, and decreased (p < 0.05) serum malonaldehyde (MDA) concentration at day 35 compared with CON. There was no significant difference in serum catalase (CAT) activity among treatments. Birds in LCE group had lower (p < 0.05) MDA concentration and higher SOD activity in liver than those in CON and ANT groups at day 35. Birds in LCE group had higher (p < 0.05) phagocytic index and serum antibody titers to Newcastle disease virus (NDV) than those in CON group. Lower (p < 0.05) concentrations of pro-inflammatory cytokines and higher (p < 0.05) concentrations of anti-inflammatory cytokines in serum and liver were observed in birds fed LCE diet than those fed CON diet. In conclusion, dietary supplementation of LCE improved growth performance by enhancing antioxidant capacity, strengthening immune system and alleviating inflammation, which has potential as antibiotic alternatives

1st ICLR International Workshop on Privacy, Accountability, Interpretability, Robustness, Reasoning on Structured Data (PAIR^2Struct)

Recent years have seen advances on principles and guidance relating to accountable and ethical use of artificial intelligence (AI) spring up around the globe. Specifically, Data Privacy, Accountability, Interpretability, Robustness, and Reasoning have been broadly recognized as fundamental principles of using machine learning (ML) technologies on decision-critical and/or privacy-sensitive applications. On the other hand, in tremendous real-world applications, data itself can be well represented as various structured formalisms, such as graph-structured data (e.g., networks), grid-structured data (e.g., images), sequential data (e.g., text), etc. By exploiting the inherently structured knowledge, one can design plausible approaches to identify and use more relevant variables to make reliable decisions, thereby facilitating real-world deployments

Operating principle of Soft Open Points for electrical distribution network operation

Soft Open Points (SOPs) are power electronic devices installed in place of normally-open points in electrical power distribution networks. They are able to provide active power flow control, reactive power compensation and voltage regulation under normal network operating conditions, as well as fast fault isolation and supply restoration under abnormal conditions. Two control modes were developed for the operation of an SOP, using back-to-back voltage-source converters (VSCs). A power flow control mode with current control provides independent control of real and reactive power. A supply restoration mode with a voltage controller enables power supply to isolated loads due to network faults. The operating principle of the back-to-back VSCs based SOP was investigated under both normal and abnormal network operating conditions. Studies on a two-feeder medium-voltage distribution network showed the performance of the SOP under different network-operating conditions: normal, during a fault and post-fault supply restoration. During the change of network operating conditions, a mode switch method based on the phase locked loop controller was used to achieve the transitions between the two control modes. Hard transitions by a direct mode switching were noticed unfavourable, but seamless transitions were obtained by deploying a soft cold load pickup and voltage synchronization process

Benefits analysis of Soft Open Points for electrical distribution network operation

Soft Open Points (SOPs) are power electronic devices installed in place of normally-open points in electrical power distribution networks. They are able to provide active power flow control, reactive power compensation and voltage regulation under normal network operating conditions, as well as fast fault isolation and supply restoration under abnormal conditions. A steady state analysis framework was developed to quantify the operational benefits of a distribution network with SOPs under normal network operating conditions. A generic power injection model was developed and used to determine the optimal SOP operation using an improved Powell’s Direct Set method. Physical limits and power losses of the SOP device (based on back to back voltage-source converters) were considered in the model. Distribution network reconfiguration algorithms, with and without SOPs, were developed and used to identify the benefits of using SOPs. Test results on a 33-bus distribution network compared the benefits of using SOPs, traditional network reconfiguration and the combination of both. The results showed that using only one SOP achieved a similar improvement in network operation compared to the case of using network reconfiguration with all branches equipped with remotely controlled switches. A combination of SOP control and network reconfiguration provided the optimal network operation

Improving lignocellulose thermal stability by chemical modification with boric acid for incorporating into polyamide

The preparation of bio-composites based on engineering plastic is always restricted by the low thermal stability of lignocellulose. In this study, the thermal stability of lignocellulose was improved by boric acid modification. Then, the borated lignocellulose was characterized to analyze the mechanism of involved in the improvement of thermal stability. Furthermore, the untreated and borated lignocellulose was combined with polyamide 6 to produce bio-composites. The effects of lignocellulose content and boric acid modification on the color, thermal stability and mechanical properties of the resulting composites were compared and analyzed. Boric acid protected lignocellulose from thermal degradation, increasing the lightness of the resulting composites. However, boric acid appeared to have a negative effect on the mechanical strength of the resulting composites. In summary, this study demonstrated that bio-composites based on engineering plastic could be prepared by improving the thermal stability of lignocellulose using a boric acid treatment