Mixed H^2/H^∞ Estimation: Preliminary Analytic Characterization And A Numerical Solution

We introduce and motivate the problem of mixed H^2/H∞ estimation by studying the stochastic and deterministic approaches of H^2 and H^∞ estimation. Mixed H^2/H^∞ estimators have the property that they have the best average performance over all estimators that achieve a certain worst-case performance bound. They thus allow a tradeoff between average and worst-case performances. In the finite horizon case, we obtain a numerical solution (based on convex optimization methods) for the optimal mixed H^2/H^∞ estimator. We also give some analytic characterizations, both on this optimal solution, and on the set of all estimators achieving a guaranteed worst-case bound. A numerical example is also provided

Design of optimal mixed H_2/H_∞ static state feedback controllers

Despite advances in robust control theory, the robust performance problem formulated in the mixed H_2/H_∞ framework largely remains an open problem. In this approach, one seeks a controller that minimizes the H_2 norm of a closed-loop map over all admissible controllers while satisfying an H_∞ constraint on another closed-loop map. Unlike the optimal H_2 problem or the γ-level sub-optimal H_∞ problem, the mixed H_2/H_∞ problem does not have a readily computable solution. In the paper we restrict consideration to static state feedback controllers and propose an efficient iterative algorithm for computing the optimal H_2/H_∞ solution

Integrated optical source of polarization entangled photons at 1310 nm

We report the realization of a new polarization entangled photon-pair source based on a titanium-indiffused waveguide integrated on periodically poled lithium niobate pumped by a CW laser at $655 nm$. The paired photons are emitted at the telecom wavelength of $1310 nm$ within a bandwidth of $0.7 nm$. The quantum properties of the pairs are measured using a two-photon coalescence experiment showing a visibility of 85%. The evaluated source brightness, on the order of $10^5$ pairs $s^{-1} GHz^{-1} mW^{-1}$, associated with its compactness and reliability, demonstrates the source's high potential for long-distance quantum communication.Comment: There is a typing mistake in the previous version in the visibility equation. This mistake doesn't change the result

An adaptive minimum spanning tree multielement method for uncertainty quantification of smooth and discontinuous responses

A novel approach for nonintrusive uncertainty propagation is proposed. Our approach overcomes the limitation of many traditional methods, such as generalized polynomial chaos methods, which may lack sufficient accuracy when the quantity of interest depends discontinuously on the input parameters. As a remedy we propose an adaptive sampling algorithm based on minimum spanning trees combined with a domain d

Distribution, Host Range and Bionomics of Rhopalosiphum nymphaeae (Linnaeus, 1761) a Polyphagous Aphid in Aquatic Vegetables

The present study records the occurrence of water lily aphid, Rhopalosiphum nymphaeae (Linn, 1971) on different aquatic plants from Varanasi and adjoining regions, Uttar Pradesh, India for the fi rst time. Both nymphs and adults prefer to feed on petiole, leaf lamina and buds towards terminal portion of different aquatic plants. They suck the cell sap resulting in curling of leaves, stunted plant growth with lower number of fruits in water chestnut. Further, the honey dew deposited on the leaves favours the development of black sooty-mould and hinders the normal photosynthetic activity of the plants. Infestation of aphid started in the region on water chestnut during last week of October (1.35 aphids leaf-1) coinciding with the initiation of winter in the region and gradually increased with highest peak (21.95 aphids leaf-1) during fourth week of January. Amongst the different aquatic host plants under study in the region, olfactometer study showed significantly highest number of R. nymphaeae (28%) attraction towards lotus followed by of water chestnut (21.3%) and water lily (20%) and the least was with water hyacinth (4%). Amongst the biopesticides tested, L. lecanii @ 5 g lit-1was found most promising with lowest median lethal time (31.09 h) followed by neem oil (1%) (41.59 h) and M. anisopliae (43.95 h)

Fusing machine learning strategy with density functional theory to hasten the discovery of MXenes for hydrogen generation

The complexity of the topological and combinatorial configuration space of MXenes can give rise to gigantic design challenges that cannot be addressed through traditional experimental or routine theoretical approaches. To this end, we establish a robust and more broadly applicable multistep workflow from the toolbox of supervised machine learning (ML) algorithms for predicting the hydrogen evolution reaction (HER) activity over 4,500 MM$^{\prime}$XT$_2$-type MXenes, where 25\% of the material space (1125 systems) is randomly selected to evaluate the HER performance using density functional theory (DFT) calculations. As the most desirable ML model, the random forest regression method with recursive feature elimination and hyperparameter optimization accurately and rapidly predicts the Gibbs free energy of hydrogen adsorption ($\Delta$G$_{H}$) with a low predictive mean absolute error of 0.374 eV. Based on these observations, the H-atom adsorbed directly on top of the outermost metal atomic layer of the MM$^{\prime}$XT$_2$-type MXenes (site-2) with Nb, V, Mo, Cr and Ti metals composed of carbon based O-functionalization are discovered to be highly stable and active catalysts, surpassing that of commercially available platinum based counterparts. Overall, the physically meaningful predictions and insights of the developed ML/DFT-based multistep workflow will open new avenues for accelerated screening, rational design and discovery of potential HER catalysts

Modulation of ISOs by land-atmosphere feedback and contribution to the interannual variability of Indian summer monsoon

A mechanism of internal variability of Indian summer monsoon through the modulation of intraseasonal oscillation (ISO) by land-atmosphere feedback is proposed. Evidence of feedback between surface soil moisture and ISOs is seen in the soil moisture data from GSWP-2 and rainfall data from observations. Using two sets of internal simulation by a regional climate model (RCM), it is shown that internally generated anomalous soil moisture interacts with the following ISO and generates interannual variability. To gain further insight, 27 years of sensitivity experiment by prescribing wet (dry) soil moisture condition during break (active) period along with a control simulation are carried out. The sensitivity experiment reveals the large-scale nature of soil moisture and ISO feedback which takes place through the changes in atmospheric stability by altering lower-level atmospheric conditions. The feedback is inherent to the monsoon system and a part of it acts through the intraseasonal varying memory of soil moisture. The RCM used to test the hypothesis is constrained by one-way interactions at the lateral boundary. Experiments with a much larger domain upheld the findings and hence suggest the true nature of soil moisture and ISO feedback present in the monsoon system