Privacy preserving distributed optimization using homomorphic encryption

This paper studies how a system operator and a set of agents securely execute a distributed projected gradient-based algorithm. In particular, each participant holds a set of problem coefficients and/or states whose values are private to the data owner. The concerned problem raises two questions: how to securely compute given functions; and which functions should be computed in the first place. For the first question, by using the techniques of homomorphic encryption, we propose novel algorithms which can achieve secure multiparty computation with perfect correctness. For the second question, we identify a class of functions which can be securely computed. The correctness and computational efficiency of the proposed algorithms are verified by two case studies of power systems, one on a demand response problem and the other on an optimal power flow problem.Comment: 24 pages, 5 figures, journa

On privacy preserving data release of linear dynamic networks

Distributed data sharing in dynamic networks is ubiquitous. It raises the concern that the private information of dynamic networks could be leaked when data receivers are malicious or communication channels are insecure. In this paper, we propose to intentionally perturb the inputs and outputs of a linear dynamic system to protect the privacy of target initial states and inputs from released outputs. We formulate the problem of perturbation design as an optimization problem which minimizes the cost caused by the added perturbations while maintaining system controllability and ensuring the privacy. We analyze the computational complexity of the formulated optimization problem. To minimize the $\ell_0$ and $\ell_2$ norms of the added perturbations, we derive their convex relaxations which can be efficiently solved. The efficacy of the proposed techniques is verified by a case study on a heating, ventilation, and air conditioning system.Comment: 18 pages, 5 figures, journa

Teacher Efficacy, Work Engagement, and Social Support Among Chinese Special Education School Teachers

This paper investigates the relationship between teacher efficacy and sociodemographic factors, work engagement, and social support among Chinese special education school teachers. The sample comprised 1,027 special education school teachers in mainland China. The Teachers’ Sense of Efficacy Scale, the Multi-Dimensional Scale of Perceived Social Support, and the Utrecht Work Engagement Scale were used for data collection. Correlation analysis revealed that social support, work engagement, and teacher efficacy were significantly correlated with each other. Additionally, gender, years of experience, and monthly salary were significant predictors of teacher efficacy. Furthermore, structural equation modeling analysis showed that social support exerted its indirect effect on teacher efficacy through the mediation of work engagement. The findings of this study provide a new perspective on the complex association between social support and teacher efficacy. The explanations and limitations of these findings are discussed

Unified Equivalent-circuit Models for Voltage-source Inverters that Capture Averaged Dynamics and Power-flow Solutions in Distribution Networks

This paper demonstrates how three-phase distribution networks composed of voltage-source inverters can be modeled as a single unified equivalent-circuit network realized with familiar circuit elements. Such a model is derived by representing all physical- and control-subsystem dynamics as equivalent circuits. Two versions are put forth: the first captures averaged dynamics; while the second is a steady-state version of the first and it captures the power-flow solution in sinusoidal steady state. The main challenge in undertaking such an effort is presented by the fact that inverters are composed of subsystems (filters, pulse width modulators, phase-locked loops, controllers, direct-quadrature reference-frame transformations) that belong to multiple domains (physical and control). We demonstrate how all these constituent subsystems can be transcribed as equivalent circuits which then promote a single and unified circuit model that captures network physical- and control-layer dynamics. Numerical simulations for a representative distribution network compare results from the averaged model and the steady-state model with high-fidelity switch-level simulations. The results establish the validity of the circuit-based models and the computational benefits of the proposed approach