VERTICES: Efficient Two-Party Vertical Federated Linear Model with TTP-aided Secret Sharing

Vertical Federated Learning (VFL) has emerged as one of the most predominant approaches for secure collaborative machine learning where the training data is partitioned by features among multiple parties. Most VFL algorithms primarily rely on two fundamental privacy-preserving techniques: Homomorphic Encryption (HE) and secure Multi-Party Computation (MPC). Though generally considered with stronger privacy guarantees, existing general-purpose MPC frameworks suffer from expensive computation and communication overhead and are inefficient especially under VFL settings. This study centers around MPC-based VFL algorithms and presents a novel approach for two-party vertical federated linear models via an efficient secret sharing (SS) scheme with a trusted coordinator. Our approach can achieve significant acceleration of the training procedure in vertical federated linear models of between 2.5x and 6.6x than other existing MPC frameworks under the same security setting

Dual-confined SeS2 cathode based on polyaniline-assisted double-layered micro/mesoporous carbon spheres for advanced Li-SeS(2 )battery

Selenium-sulfur solid solutions (SexSy) attracts soaring attention owing to its improved electrical conductivity over sulfur and higher theoretical specific capacity than selenium. Herein, high-performance lithium-selenium/sulfur batteries with a dual-confined cathode configuration by encapsulating SeS2 in double-layered hollow micro/mesoporous carbon spheres (DSMCs) with a conductive polyaniline (PANI) protection sheath are proposed. Polysulfides/polyselenides are efficiently restricted in the cathode via physical and chemical entrapment from DSMCs and PANI as well as chemical binding between selenium and sulfur. Benefiting from the distinct advantages of SeS2 and the well-constructed host framework, the cathode achieves high capacity utilization of 1018 mAh g(-1) at 0.2 A g(-1) , together with outstanding rate capability of 619 mAh g(-1) at 2 A g(-1) and excellent cycle life over 500 cycles with almost 100% Coulombic efficiency. The novel SexSy based cathode demonstrates a promising route to surmount some bottlenecks of current lithium-sulfur systems for high-performance rechargeable batteries

A SIMP based Methodology for Topology Optimization and its Application to Piezoelectric Energy Harvester Designs

International audienc

Multiple core-shelled sulfur composite based on spherical double-layered hollow carbon and PEDOT:PSS as cathode for lithium-sulfur batteries

Nanostructured sulfur cathode with a multiple core-shelled structure, featured with the spherical double-layered hollow carbon/sulfur composite (DLHC/S) coated with a conductive layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), is designed and synthesized for lithium-sulfur batteries. Transmission electron microscope images of DLHC/S single nanoparticle show that the sulfur aggregates predominantly in the interior space between the two carbon shells by using a vacuum infiltration process. The electric conductivity of DLHC/S@PEDOT:PSS increases over 5 times as comparing to DLHC/S without PEDOT:PSS coating. The composite cathode exhibits a high reversible capacity of 1089 mAh g(-1) at 0.2C and superior rate capacity of 510 mAh g(-1 )even at 4 C, and also remarkable cycling stability with a capacity decay of 0.097% per cycle after 500 cycles at 1 C. The excellent electrochemical performances for DLHC/S@PEDOT:PSS cathode are primarily attributed to the engineering of the unique multiple core-shell structure of DLHC/S@PEDOT:PSS, which inhibits the sulfur dissolution into the electrolyte and the polysulfide shuttle effect, together with the conductivity enhancement due to PEDOT:PSS coating. (C) 2020 Elsevier B.V. All rights reserved

A Multi-Objective Topology Optimization Methodology and its Application to Electromagnetic Actuator Designs

International audienceIn this article, a multi-objective topology optimization (MOTO) methodology based on the hybridization of the Non-dominated Sorting Genetic Algorithm II (NSGAII) and Differential Evolutionary (DE) algorithm is proposed. The framework of the proposed hybrid multiobjective optimization (MOO) algorithm is elaborated, and its performances and advantages over existing standard MOO methods are evaluated and demonstrated by solving typical mathematical test functions. To validate the proposed hybrid MOTO methodology, it is applied to the topology optimization of an electromagnetic actuator. Both linear and nonlinear cases are investigated. The numerical results demonstrate that a set of novel topologies with improved multiple objectives is obtained

Development of a High-Resolution All-Fiber Homodyne Laser Doppler Vibrometer

Based on the homodyne detection, a compact and cost-effective all-fiber laser Doppler vibrometer (LDV) with high resolution is presented. For the signal processing, the discrimination algorithm combined with the nonorthogonal correction is applied. The algorithm corrects the quadrature imbalance and other nonlinearity. In the calibration experiment, with the glass pasted on a piezoceramic transducer (PZT), the velocity resolution of 62 nm/s at 4 kHz and displacement resolution of 2.468 pm are achieved. For the LDV-based acousto-optic communication, the minimum detectable sound pressure level (SPL) reached 0.12 Pa under the hydrostatic air-water surface. The results demonstrate that the designed homodyne LDV has a low system background noise and can offer high precision in the vibration measurement

Synthesis of silicon oxycarbonitride nanosphere as cathode host for lithium-sulfur batteries

Silicon oxycarbonitride (SiOCN) composites with different carbon contents were synthesized by pyrolysis of precursors generated from aldimine condensation of 3-aminopropyltriethoxysilane (APTES) with different aldehydes and simultaneous hydrolysis of APTES. Both SiOCN-1 and SiOCN-5 composites, derived from formaldehyde and glutaraldehyde respectively, display similar bulky structure composed by aggregated nanospheres with a diameter of 70-100 nm. SiOCN-5 has a higher carbon content of 30.4% than 15.9% for SiOCN-1, while a lower specific surface area of 38.2 m(2) g(-1) than 76.0 m(2) g(-1) for SiOCN-1. SiOCN/S cathodes with sulfur loading of 1.2-1.5 mg cm(-2) were fabricated using SiOCN as sulfur host on different current collector of aluminum foil (AL) or carbon paper (CP). When using aluminum foil as current collector, SiOCN-5/S-AL cathode exhibits better electrochemical performance than SiOCN-1/S-AL, primarily due to the higher electrical conductivity of SiOCN-5 comparing with SiOCN-1. When using porous carbon paper as current collector, SiOCN-5/S-CP cathode shows the best cycling performance with a discharge capacity of 648.9 mA h g(-1) at 0.2C after 100 cycles. Even at a high rate of 1C, SiOCN-5/SCP also exhibits an excellent cycling stability, delivering a reversible discharge capacity of 374.5 mA h g(-1) after 500 cycles with a capacity retention of 73.0%. (C) 2020 Elsevier B.V. All rights reserved

Landscape metrics in assessing how the configuration of urban green spaces affects their cooling effect: A systematic review of empirical studies

Urban green spaces (UGS) are effective mitigations to excessive urban heat. Landscape metrics (LMs) have been widely used to assess how UGS configuration, i.e., edge and area, shape complexity, and aggregation, may facilitate better cooling. However, application of configurational LMs has produced diverging suggestions for planning and design practice, which cannot provide urban and landscape designers with holistic insights for future sustainable development. Thus, we conducted a systematic review to (1) summarize the contextual and methodological factors in pertinent studies, and (2) synthesize extractable results and implications, and see if the contextual and methodological factors may help to interpret the diversity in planning and design implications. A total of 167 studies were identified, covering 90 cities in 27 countries belonging to 16 Köppen climate zones. Evolving statistical methods have been applied, including spatial, non-spatial, and non-parametric machine-learning analyses. Synthesis of correlation coefficients reveals that patch-level metric SHAPE, and class-level metrics LPI, AI and COHESION yielded generally consistent trends across studies. No consensus was obtained based on patch-level metrics, while class-level analyses suggest aggregated, patchy, larger, and complex-shaped UGS facilitate better cooling. Contextual and methodological factors cannot help interpret the diverging suggestions. Few specific planning and design implications on UGS configuration were given. Future studies are suggested to specify either a land-use or land-cover perspective to align with practical scales in planning and design practice, and to formulate specific implications beyond binary suggestions by echoing the heterogeneity of thermal environment and UGS pattern under precise planning and design contexts with practical illustration