Privacy preservation is addressed for decentralized optimization, where N agents cooperatively minimize the sum of N convex functions private to these individual agents. In most existing ...decentralized optimization approaches, participating agents exchange and disclose states explicitly, which may not be desirable when the states contain sensitive information of individual agents. The problem is more acute when adversaries exist which try to steal information from other participating agents. To address this issue, we propose a privacy-preserving decentralized optimization approach based on alternating direction method of multipliers (ADMM) and partially homomorphic cryptography. To the best of our knowledge, this is the first time that cryptographic techniques are incorporated in a fully decentralized setting to enable privacy preservation in decentralized optimization in the absence of any third party or aggregator. To facilitate the incorporation of encryption in a fully decentralized manner, we introduce a new ADMM, which allows time-varying penalty matrices and rigorously prove that it has a convergence rate of O(1/t) . Numerical and experimental results confirm the effectiveness and low-computational complexity of the proposed approach.
The current outbreak of the coronavirus (COVID-19) pandemic has significantly increased the global usage of antiviral drugs (AVDs), leading to higher concentrations of antibiotics in water pollution. ...To address this current issue, a new kind of adsorbent named isostructural zeolitic tetrazolate imidazolate frameworks (ZTIFs) were synthesized by combining imidazole and tetrazolates into one self-assembly approach by adjusting pores and stability of frameworks. The incorporation of imidazole ligand progressively increased the stability of frameworks. Furthermore, increasing the content of tetrazolate ligand greatly improved the adsorption performance due to N-rich sites by increasing the pore size. The obtained adsorbent composite exhibits macroporous structure up to 53.05 nm with excellent structural stability. Owing to their macropores and highly exposed active sites, the synthesized ZTIFs exhibit the maximum adsorption capacity for oseltamivir (OT) and ritonavir (RT) of 585.2 mg/g and 435.8 mg/g, respectively. Moreover, the adsorption uptake and saturation process were rapid compared to simple MOF. Within 20 min, both pollutants achieved equilibrium. The adsorption isotherms were best interpreted by Pseudo second order kinetics. The adsorption of AVDs on ZTIFs was spontaneous, exothermic, and thermodynamically feasible. The DFT calculations and characterization results after adsorption demonstrate that π-π interaction, pore filling, surface complexation, and electrostatic interaction were the primary features of the adsorption mechanism. The prepared ZTIFs composite exhibits high chemical, mechanical and thermal stability and can be recycled multiple times without destroying its morphology and structure. The adsorbent regeneration for several cycles impacted the operational cost and the eco-friendly characteristic of the process.
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Average consensus underpins key functionalities of distributed systems ranging from distributed information fusion, decision-making, distributed optimization, to load balancing and decentralized ...control. Existing distributed average consensus algorithms require each node to exchange and disclose state information to its neighbors, which is undesirable in cases where the state is private or contains sensitive information. In this paper, we propose a novel approach that avoids disclosing individual state information in average consensus by letting each node decompose its state into 2 substates. For each node, one of the two substates involves in computation and internode interactions as if it were the original state, while the other substate interacts only with the first substate of the same node, being completely invisible to other nodes. The initial values of the two substates are chosen randomly but with their mean fixed to the initial value of the original state, which is key to guarantee convergence to the desired consensus value. In direct contrast to differential-privacy based privacy-preserving average-consensus approaches, which enable privacy by compromising accuracy in the consensus value, the proposed approach can guarantee convergence to the exact desired value without any error. Not only is the proposed approach able to prevent the disclosure of a node's initial state to honest-but-curious neighbors, it can also provide protection against inference by external eavesdroppers able to wiretap communication links. Numerical simulations demonstrate the effectiveness of the approach and its advantages over state-of-the-art counterparts.
This paper deals with the problem of asymptotically stabilizing the splay state configuration of a network of identical pulse coupled oscillators through the design of the their phase response ...function. The network of pulse coupled oscillators is modeled as a hybrid system. The design of the phase response function is performed to achieve almost global asymptotic stability of a set, wherein oscillators' phases are evenly distributed on the unit circle. To establish such a result, a novel Lyapunov function is proposed. Robustness with respect to frequency perturbation is assessed. Finally, the effectiveness of the proposed methodology is shown in an example.
The poor delivery efficiency remains a major challenge in nanomaterial based tumor targeted imaging and drug delivery. This work demonstrated a strategy to improve nanoparticle delivery and ...intratumoral distribution using a sub-5 nm (3.5 nm core size) ultrafine iron oxide nanoparticles (uIONPs) that can easily extravasate from the tumor vasculature and readily diffuse into the tumor tissue compared to iron oxide nanoparticles (IONP) with larger sizes, followed by self-assembling in the acidic tumor interstitial space to limit their re-entering the circulation. By combining enhanced extravasation and reduced intravasation, improved delivery and tumor retention of nanoparticles are achieved. Multi-photon imaging of mice bearing orthotopic tumors co-injected with fluorescent dye labeled nanoparticles with different sizes showed that uIONPs exhibited more efficient extravasation out of tumor vessels and penetrated deeper into the tumor than larger sized IONP counterparts. Moreover,
in vivo
magnetic resonance imaging (MRI) revealed that uIONPs exhibited “bright” T
1
contrast when dispersed in the tumor vasculature and peripheral area at 1 hour after intravenous administration, followed by emerging “dark” T
2
contrast in the tumor after 24 hours. Observed T
1
–T
2
contrast switch indicated that uIONPs single-dispersed in blood with T
1
contrast may self-assemble into larger clusters with T
2
contrast after entering the tumor interstitial space. Improved passive targeting and intratumoral delivery along with increased tumor retention of uIONP are due to both easy extravasation into the tumor when single-dispersed and restricting intravasation back into circulation after forming clusters, thus, exerting the enhanced permeability and retention (EPR) effect for nanoparticle delivery to tumors.
Synchronization of pulse-coupled oscillators (PCOs) has gained significant attention recently due to their increased applications in sensor networks and wireless communications. Given the distributed ...and unattended nature of wireless sensor networks, it is imperative to enhance the resilience of PCO synchronization against malicious attacks. However, most existing results on attack-resilient pulse-based synchronization are obtained under assumptions of all-to-all coupling topologies or restricted initial phase distributions. In this paper, we propose a new pulse-based synchronization mechanism to improve the attack resilience of PCO synchronization that is applicable to non-all-to-all networks. Under the proposed synchronization mechanism, we prove that perfect synchronization of legitimate oscillators can be guaranteed in the presence of multiple Byzantine attackers who can emit attack pulses arbitrarily without any constraint except that practical bit rate constraint renders the number of pulses from an attacker to be finite. The new mechanism can guarantee synchronization even when the initial phases of all legitimate oscillators are arbitrarily distributed in the entire oscillation period, which is in distinct difference from most existing attack-resilient synchronization approaches (including the seminal paper from Lamport and Melliar-Smith <xref ref-type="bibr" rid="ref1">1 ) that require a priori (almost) synchronization among legitimate oscillators. Numerical simulation results are given to confirm the theoretical results.
Poor delivery efficiency remains a major challenge in nanomaterial-based tumor-targeted imaging and drug delivery. This work demonstrates a strategy to improve nanoparticle delivery and intratumoral ...distribution using sub-5 nm (3.5 nm core size) ultrafine iron oxide nanoparticles (uIONP) that can easily extravasate from the tumor vasculature and readily diffuse into the tumor tissue compared to the iron oxide nanoparticle (IONP) with larger sizes, followed by self-assembling in the acidic tumor interstitial space to limit their re-entering into circulation. By combining enhanced extravasation and reduced intravasation, we achieved improved delivery and tumor retention of nanoparticles. Multiphoton imaging of mice bearing orthotopic tumors co-injected with fluorescent dye-labeled nanoparticles with different sizes showed that uIONPs exhibited more efficient extravasation out of tumor vessels and penetrated deeper into the tumor than larger sized IONP counterparts. Moreover, in vivo magnetic resonance imaging revealed that uIONPs exhibited “bright” T 1 contrast when dispersed in the tumor vasculature and peripheral area at 1 h after intravenous administration, followed by emerging “dark” T 2 contrast in the tumor after 24 h. Observed T 1–T 2 contrast switch indicated that uIONPs single-dispersed in blood with T 1 contrast may self-assemble into larger clusters with T 2 contrast after entering the tumor interstitial space. Improved passive targeting and intratumoral delivery along with increased tumor retention of uIONPs are due to both easy extravasation into the tumor when single-dispersed and restricting intravasation back into circulation after forming clusters, thus exerting the enhanced permeability and retention effect for nanoparticle delivery to tumors.
Along with the rapid development of industry, VOCs gradually move into the spotlight, and now become a kind of harmful environmental pollutants that cannot be overlooked. This paper introduces the ...hazards of VOCs and the common catalytic combustion catalysts, noble metal catalysts and non-noble metal catalysts, for the elimination of VOCs. Perovskite catalysts, as one of the non-noble catalysts, play an important role in the field of catalytic combustion in recent years. According to the classification of elements doping in perovskites, the research achievements in the past five years were analyzed and reviewed. In addition, this paper also analyzes and elaborates the reaction kinetics and QSAR/QSPR models for the introduction of structural properties and reaction mechanisms.
Fault detection of networked control systems (NCS) subject to uncertain time-varying delay is studied in this paper. For the convenience of residual generator design, influence caused by ...network-induced delay is first transformed into time-varying polytopic uncertainty, which greatly facilitates further manipulation. Then design of the optimal residual generator is formulated as a model matching problem, i.e., to design a residual generator best matching the optimal residual generator of NCS in the delay free case. This procedure is assisted by parameter-dependent Lyapunov function matrix based bounded real lemma, which has been proved to be much better than single constant Lyapunov function matrix based results. This approach not only can be used in conditions that the variation part of the delay is less than one sampling period, but also can be applied to scenarios where the variation part of the delay is larger than one sampling period. Simulation results are also given to illustrate effectiveness of the proposed method.
This paper proposes a new class of phase shifters using right-angled triangular patches based on the substrate integrated suspended line (SISL) platform. The reference line and the main line of the ...phase shifter are both designed in the patch form, which is different from previous works. With the common reference patch fixed, multiway and polyphase SISL phase shifters can be achieved by adjusting the main patch. As demonstration, three SISL patch-based phase shifters with phase shifts of 45°, 60°, and 90°, respectively, have been designed at 24-GHz band and fabricated by the printed circuit board (PCB) process. The radiation loss, conductor loss, and dielectric loss of the proposed patch-based phase shifters have been reduced based on the self-packaged SISL platform, and the measured insertion loss of the SISL phase shifter has a typical value of 0.3 dB at 24-GHz band, which is much smaller as compared with the state of the art. Moreover, the 90° case has been applied to an SISL single-balanced mixer design. Besides the low-loss phase shifter, other components of the mixer are all implemented on the common SISL platform with low loss, and the overall loss of the SISL mixer is very small as compared with the other works. The SISL mixer has a compact size and low conversion loss with a minimum of 5.8 dB at the 24-GHz band.
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