208 research outputs found

    Bayesian Persuasion for Containing SIS Epidemic with Asymptomatic Infection

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    We investigate the strategic behavior of a large population of agents who decide whether to adopt a costly partially effective protection or remain unprotected against the susceptible-infected-susceptible epidemic. In contrast with most prior works on epidemic games, we assume that the agents are not aware of their true infection status while making decisions. We adopt the Bayesian persuasion framework where the agents receive a noisy signal regarding their true infection status, and maximize their expected utility computed using the posterior probability of being infected conditioned on the received signal. We completely characterize the stationary Nash equilibrium of this setting, and identify conditions under which partial information disclosure leads to a smaller proportion of infected individuals at the equilibrium compared to full information disclosure, and vice versa

    Low-Frequency Carrier Kinetics in Triple Cation Perovskite Solar Cells Probed by Impedance and Modulus Spectroscopy

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    Organometallic halide perovskites-based solar cells have emerged as next-generation photovoltaic technology. However, many of its intriguing optoelectronic properties at low frequency are highly debated. Here, we investigate the low-frequency carrier kinetics of the state-of-the-art triple cation perovskite Cs0.06FA0.79MA0.15Pb(I0.85Br0.15)3 solar cells using bias-dependent impedance and modulus spectroscopy under dark and illumination conditions. We observe a strong dependence of dielectric permittivity on frequency in 1 Hz to 1 MHz region with a dielectric relaxation, which is observed to follow the Maxwell-Wagner type interfacial polarization possibly originating from the grain boundary/ionic defects. Furthermore, correlating the impedance and modulus spectra reveals the localized charge carrier relaxation in this triple cation device from which we obtain a phenomenological picture of the hopping process and developing an understanding of the charge carrier kinetics in these high-efficiency perovskite photovoltaics

    Coupled Evolutionary Behavioral and Disease Dynamics under Reinfection Risk

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    We study the interplay between epidemic dynamics and human decision making for epidemics that involve reinfection risk; in particular, the susceptible-infected-susceptible (SIS) and the susceptible-infected-recovered-infected (SIRI) epidemic models. In the proposed game-theoretic setting, individuals choose whether to adopt protection or not based on the trade-off between the cost of adopting protection and the risk of infection; the latter depends on the current prevalence of the epidemic and the fraction of individuals who adopt protection in the entire population. We define the coupled epidemic-behavioral dynamics by modeling the evolution of individual protection adoption behavior according to the replicator dynamics. For the SIS epidemic, we fully characterize the equilibria and their stability properties. We further analyze the coupled dynamics under timescale separation when individual behavior evolves faster than the epidemic, and characterize the equilibria of the resulting discontinuous hybrid dynamical system for both SIS and SIRI models. Numerical results illustrate how the coupled dynamics exhibits oscillatory behavior and convergence to sliding mode solutions under suitable parameter regimes.Comment: arXiv admin note: text overlap with arXiv:2203.1027

    Strong Coupling of Self-Trapped Excitons to Acoustic Phonons in Bismuth Perovskite Cs3Bi2I9\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9}

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    To assess the potential optoelectronic applications of metal-halide perovskites, it is critical to have a detailed understanding of the nature, strength, and dynamics of the interactions between carriers and the polar lattices. Here, we report the electronic and structural dynamics of bismuth-based perovskite Cs3Bi2I9\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9} revealed by transient reflectivity and ultrafast electron diffraction. A cross-examination of these experimental results combined with theoretical analyses allows the identification of the major carrier-phonon coupling mechanism and the associated time scales. It is found that carriers photoinjected into Cs3Bi2I9\textrm{Cs}_{3}\textrm{Bi}_{2}\textrm{I}_{9} form self-trapped excitons on an ultrafast time scale. However, they retain most of their energy and their coupling to Fr\"ohlich-type optical phonons is limited at early times. Instead, the long-lived excitons exert an electronic stress via deformation potential and develop a prominent, sustaining strain field as coherent acoustic phonons in 10 ps. From sub-ps to ns and beyond, a similar extent of the atomic displacements is found throughout the different stages of structural distortions, from limited local modulations to a coherent strain field to the Debye-Waller random atomic motions on longer times. The current results suggest the potential use of bismuth-based perovskites for applications other than photovoltaics to take advantage of carriers' stronger self-trapping and long lifetime.Comment: 21 pages, 4 figures for the main tex

    Waveform Agile Sensing Approach for Tracking Benchmark in the Presence of ECM using IMMPDAF

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    This paper presents an efficient approach based on waveform agile sensing, to enhance the performance of benchmark target tracking in the presence of strong interference. The waveform agile sensing library consists of different waveforms such as linear frequency modulation (LFM), Gaussian frequency modulation (GFM) and stepped frequency modulation (SFM) waveforms. Improved performance is accomplished through a waveform agile sensing technique. In this method, the selection of waveform to be transmitted at each scan is determined, by jointly computing ambiguity function of waveform and Cramer-Rao Lower Bound (CRLB) matrix of measurement errors. Electronic counter measures (ECM) comprises of stand-off jammer (SOJ) and self-screening jammer (SSJ). Interacting multiple model probability data association filter (IMMPDAF) is employed for tracking benchmark trajectories. Experimental results demonstrate that, waveform agile sensing approach require only 39.98 percent lower mean average power compared to earlier studies. Further, it is observed that the position and velocity root mean square error values are decreasing as the number of waveforms are increasing from 5 to 50

    Carbon-based adsorbents from naturally available Bermuda grasses : removal of TDS and arsenic ions

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    In the present study, we have reported the synthesis of nano porous carbon material (GC) by the thermal treatment of the commonly available Bermuda grasses, and metal oxides doped bio-compatible polymer chitosan-GC based porous cross-linked composites (CHGCCZ) as adsorbent materials for the removal of total dissolved solids (TDS) and efficient removal of arsenic (As(V)) ions from aqueous medium, respectively. The synthesized adsorbents have been characterized by FTIR, PXRD, FESEM, TGA, and the systematic investigations have shown that the incorporation of GCs into cross-linked matrix makes them porous, more resistant to degradation, and suitable adsorption matrix for the toxic As(V) removal. The presence of As(V) ions is quantified by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) measurements. The amount of TDS and arsenic concentration was reduced to the minimum value of 103 ppm (average value∼119 ppm) from 414 ppm and 7.7 ppm from very high concentration of 10.15 ppm, respectively. The recyclability test has also been performed after regeneration of the CHGCCZ and the initial findings has been found to be promising. Therefore, we have systematically investigated the efficacy of TDS removal by GCs and As(V) adsorption properties of metal oxide doped cross-linked CHGCCZ composite from the aqueous system and demonstrated the regeneration process for CHGCCZ in our study

    Effect of Bromine Doping on Charge Transfer, Ion Migration and Stability of the Single Crystalline MAPb(BrxI1−x)3 Photodetector

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    Organic-inorganic halide perovskites (OIHPs) have emerged as a promising semiconductor for the fabrication of efficient optoelectronic devices such as photodetectors (PDs). Among all perovskite composition, the mixed-halide MAPb(BrxI1−x)3 formulations have gained more attention for the photodetection application thanks to their tunable optoelectronic properties and great stability. However, there is still a lack of sufficient understanding of the Br doping on the stability and physical properties of MAPb(BrxI1−x)3 based PDs. In this work, we prepare a series of MAPb(BrxI1−x)3 (x = 0, 0.04, 0.08, 0.12, 0.16) single crystals (SCs) and investigate the influence of the Br content on the crystal structure, charge transport, ion migration, and recombination phenomena. Moreover, self-powered PDs with a structure of Pt/MAPb(BrxI1−x)3 SCs/Pt have been developed, and their optoelectrical properties under different wavelengths of light sources (blue, green, red, and white) have been studied. We found that all the PDs exhibit the highest photoresponse under white light indicating their potential for broad spectrum detecting applications. Particularly, the MAPb(Br0.16I0.84)3 SC PD exhibits highest responsivity of 2.41 mA/W under white light intensity, while the highest detectivity of 15.41 × 1010 Jones was observed for MAPb(Br0.12I0.88)3 SC PD due to the less amount of trap states and suppressed ion migration, as proved by impedance spectroscopy. Finally, photostability and one-year shelf-life stability of the corresponding PDs are demonstrated.National Science Centr
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