Probabilistic nonlinear analysis of CFR dams by MCS using Response Surface Method

This paper presents the probabilistic analysis of concrete-faced rockfill (CFR) dams according to the Monte Carlo Simulation (MCS) results which are obtained through the Response Surface Method (RSM). ANSYS finite element program is used to get displacement and principal stress components. First of all, some parametric studies are performed according to the simple and representative finite element model of dam body to obtain the optimum approximate model. Secondly, a sensitivity analysis is performed to get the most effective parameters on dam response. Then, RSM is used to obtain the approximate function through the selected parameters. After the performed analyses, star experimental design with quadratic function without mixed terms according to the k = 1 is determined as the most appropriate model. Finally, dam-foundation-reservoir interaction finite element model is constituted and probabilistic analyses are performed with MCS using the selected parameters, sampling method, function and arbitrary factor under gravity load for empty and full reservoir conditions. Geometrically and materially nonlinearity are considered in the analysis of dam-foundation-reservoir interaction system. Reservoir water is modeled by fluid finite elements based on the Lagrangian approach. Structural connections are modeled as welded contact and friction contact based on Coulomb’s friction law. Probabilistic displacements and stresses are presented and compared with deterministic results.     

A model updating approach based on design points for unknown structural parameters

Finite element analysis has become an essential tool to estimate structural responses under static and dynamic loads. However, there are a lot of uncertainties in structural properties. For this reason, in many cases, the outcomes of the theoretical and experimental modal analyses do not match. Therefore, the analytical models of the structures need to be updated according to the experimental test results. The commonly used method to get parameters for model updating is experimental modal analysis which provides structural dynamic characteristic (natural frequencies, mode shapes and modal damping ratio). There are many methods available for the updating process. This study addresses an updating algorithm to modify the numerical models by using the design points for unknown structural properties. The proposed method aims to minimize the difference between the analytical and experimental natural frequencies by updating uncertain parameters for each mode and combine them to get an optimum solution. The algorithm is tested on a column and a 2D frame models. These models are investigated by taking the connection rigidity and elasticity modulus as unknown parameters. It is observed that the proposed algorithm gives better results for unknown structural properties compared to the initial values.     

Kinetic and mechanistic features of carbon dioxide reforming of methane over Co–Ce/ZrO2 catalysts

Carbon dioxide reforming of methane (CDRM) is an effective route to utilize CO₂ and CH₄, the most abundant, thermodynamically stable and hazardous greenhouse gases. To overcome the economical impediments to favor CDRM's industrial applicability, its mechanistic features need to be revealed both for developing efficient catalysts and optimizing operational conditions. In this context, this work aims to obtain power-law type CDRM kinetic expressions over 5%Co–2%Ce/ZrO₂ and 10%Co–2%Ce/ZrO₂ catalysts and compare and analyze mechanistic routes to elucidate the effect of the Co:Ce ratio on kinetics. The empirical power-law type rate expressions were estimated with the reaction orders of 1.63 and 1.12 for CH₄ and 0.29 and –0.12 for CO₂ for 5%Co–2%Ce/ZrO₂ and 10%Co–2%Ce/ZrO₂ catalysts, respectively. Limited CH₄ activation and, thus, carbon formation due to low Co loading lead to accumulation of surface oxygen on ZrO₂ as redox ability of Ce becomes suppressed. This causes higher CO₂ activation barrier. The presence of H₂ in the feed slows down mechanistic steps involving CH_x. The reactions including CH₄ activation, most probably reversible direct CH₄ dissociation, are found to be rate determining.     

Optimal investment with random endowments and transaction costs: duality theory and shadow prices

This paper studies the utility maximization on the terminal wealth with random endowments and proportional transaction costs. To deal with unbounded random payoffs from some illiquid claims, we propose to work with the acceptable portfolios defined via the consistent price system such that the liquidation value processes stay above some stochastic thresholds. In the market consisting of one riskless bond and one risky asset, we obtain a type of super-hedging result. Based on this characterization of the primal space, the existence and uniqueness of the optimal solution for the utility maximization problem are established using the duality approach. As an important application of the duality theorem, we provide some sufficient conditions for the existence of a shadow price process with random endowments in a generalized form similar to Czichowsky and Schachermayer (Ann Appl Probab 26(3):1888–1941, 2016) as well as in the usual sense using acceptable portfolios.

     

Cytotoxicity and Gene Expression Studies of Curcumin and Piperine Loaded Nanoparticles on Breast Cancer Cells

Russian Journal of Applied Chemistry - The aim of this study was to investigate the anticancer effects of curcumin and piperine loaded nanoparticles compared to docetaxel on the breast cancer cell...     

Arene ruthenium metallacycles containing chelating thioamide ligands

Cationic, chiral arene ruthenium complexes of the type [Ru(η⁶-cym)(PPh₃){κ²N,S-PhNC(S)R}]BPh₄ were prepared in high yields by refluxing a mixture containing [(η⁶-cym)RuCl₂]₂, Ph₃P, PhNHC(S)R, NaBPh₄ and Et₃N in MeOH. A series of seven complexes with different thioamide ligands was prepared and fully characterised by spectroscopic methods including NMR spectroscopy and electrospray mass spectrometry. The solid-state structures of two complexes were determined by single crystal X-ray diffraction.     

Inventory management with partially observed nonstationary demand

We consider a continuous-time model for inventory management with Markov modulated non-stationary demands. We introduce active learning by assuming that the state of the world is unobserved and must be inferred by the manager. We also assume that demands are observed only when they are completely met. We first derive the explicit filtering equations and pass to an equivalent fully observed impulse control problem in terms of the sufficient statistics, the a posteriori probability process and the current inventory level. We then solve this equivalent formulation and directly characterize an optimal inventory policy. We also describe a computational procedure to calculate the value function and the optimal policy and present two numerical illustrations.     

Near-infrared metamaterial films with reconfigurable transmissive/reflective properties

A near-infrared metamaterial design that is reconfigurable between almost completely transmissive and reflective states is presented. The reconfiguration is enabled by tuning the anisotropic nematic liquid crystals used as a spacer layer between two silver nanoplates in a planar doubly periodic metamaterial. The design is optimized for maximum difference in transmittance between the two states by using a genetic algorithm. For a linearly polarized illumination at normal incidence, full-wave electromagnetic analysis predicts that the optimized metamaterial film can change the transmittance between 98.7% and 0.1% at a wavelength of 1.1 microm.     

Propagation Characteristics of a Partially Coherent Gaussian Schell-model Array Vortex Beam in the Joint Turbulence Effect of a Jet Engine and Atmosphere

This work investigates the joint effects of jet engine exhaust-induced turbulence and atmospheric turbulence on the propagation of a partially coherent Gaussian Schell-model Array (GSMA) vortex beam. Using the two-process propagation method, analytical formulae are derived for the cross-spectral density, spectral density, degree of coherence, and beam width of the considered beam. The results show that the considered beam takes different shapes; when the spatial coherence is large, the spectral density of the GSMA vortex beam takes an elliptical shape, whereas when the spatial coherence is smaller, the spectral density remains a Gaussian shape. The evolution profile of the degree of coherence weakens gradually when the propagation distance, topological charge, and turbulence strength increase. Moreover, the profile of the degree of coherence takes the Gaussian profile when the propagation distance is longer or turbulence atmospheric is stronger. Furthermore, the results reveal that the corresponding beam spreads faster with a larger propagation distance, lower spatial coherence, and high-strength turbulence. This study also concludes from the results that the beam is affected more when its propagation is near the jet engine exhaust, which means that this latter has a significant impact.