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Currently, Zr-alloys are widely used in nuclear power reactors for fuel cladding and structural components. Many types of zr-based alloys were developed to overcome the challenges encountered in the progress of nuclear reactors (high-burnup and high-duty). Oxygen diffused into the cladding, hydrogen absorbed in the cladding (breakaway oxidation and ruptured balloons) and rapid oxidation rate are results of chemical interaction of cladding material with steam at high temperature. Zirconium alloys seem to be the most suitable for use in fuel cladding, if they can overcome the rapid oxidation at temperature higher than 1200 °C. Previous studies on the oxidation behavior for some Zr-alloys nuclear fuel cladding tubes in steam and steam–air atmospheres at high temperatures are reviewed. The oxidation behavior of zirconium-alloys is strongly affected by the chemical composition of alloys and its surface conditions.

Hydrogen borrowing catalysis serves as a powerful alternative to enolate alkylation, enabling the direct coupling of ketones with unactivated alcohols. However, to date, methods that enable control over the absolute stereochemical outcome of such a process have remained elusive. Here we report a catalytic asymmetric method for the synthesis of enantioenriched cyclohexanes from 1,5‐diols via hydrogen borrowing catalysis. This reaction is mediated by the addition of a chiral iridium(I) complex, which is able to impart high levels of enantioselectivity upon the process. A series of enantioenriched cyclohexanes have been prepared and the mode of enantioinduction has been probed by a combination of experimental and DFT studies.

In this article, a novel algorithm for high-accuracy partial discharge (PD) localization in an oil insulation system is proposed. This study aims to identify the statistics of the dynamics and measurement noise sequences in a PD localization system and employ that information in realizing better estimates. An extended Kalman filter (EKF) is used to estimate the PD location. The performance of the filter is enhanced by identifying the true statistics of the noise sequences using a maximum likelihood estimation approach. The accuracy of the proposed optimal algorithm is verified experimentally by estimating the PD location in an oil insulation system under two experimental settings.

The alkylation of a variety of ketones using 1° or 2° alcohols under hydrogen borrowing catalysis is described. Initial research focused on the α-alkylation of cyclopropyl ketones with higher 1° alcohols (i.e. larger than MeOH), leading to the formation of α-branched products. Our search for additional substrates with which to explore this chemistry led us to discover that di-ortho-substituted aryl ketones were also privileged scaffolds, with Ph∗ (C6Me5) ketones being the optimal choice. Further investigations revealed that this motif was crucial for alkylation with 2° alcohols forming β-branched products, which also provided an opportunity to study diastereoselective and intramolecular hydrogen borrowing processes.

Catalytic oxidative cyclisation reactions have been employed for the synthesis of the E and F rings of the complex natural product target pectenotoxin 4. The choice of metal catalyst (cobalt- or osmium-based) allowed for the formation of THF rings with either trans or cis stereoselectivity. Fragment union using a modified Julia reaction then enabled the synthesis of an advanced synthetic intermediate containing the EF and G rings of the target.

This work explores the promotion effects of employing our proposed mechanical ultrasonic-activated precipitation (MUP) technique on the different features (textural, morphological, thermal, optical, and photo/catalytic) during the synthesis of hematite nanoparticles compared to the conventional chemical precipitation pathway (CPP). X-ray diffraction data revealed the higher amorphicity, microstrains, and lattice defects for the pristine MUP products over CPP. Also, it confirmed the inverse interdependence between the lattice microstrains and the crystallite size. Microstructural and morphological analyses showed a decrease in the average particles' sizes by a factor of 20%, 28% and 39% upon applying MUP at precursor concentrations of 0.05M, 0.15M, and 0.45M, respectively. Moreover, it exhibited higher values of surface area with roughness, mesoporosity and better uniformity over CPP products. A detailed thermal study figured the interdependence correlation between the particle's crystallinity, employed pathway, and the precursor concentration, showing higher crystallinity for CPP within a shorter temperature range over the poorly crystallized MUP products. Besides, it depicted that the proper calcination temperature is

In this paper, high-accuracy estimation of partial discharge (PD) location in an oil insulation system is addressed. The study aims at forming a fault-tolerant PD localization system. Initially, the algorithm periodically and probabilistically checks for possible bias in the acoustic emission sensors’ measurements. Once the detected bias is removed from the sensors’ measurements, multiple-model extended Kalman filters are used to estimate the location of the PD. The proposed multiple-model approach is intended to compensate for increased measurement noise statistics that result from sensor aging or ambient noise. The accuracy of the proposed algorithm is verified using multiple experimental results when the PD is initiated in different locations within the oil-filled transformer tank under different working conditions.

This paper presents a sequential fault detection and identification algorithm for detecting a bias fault in the measurements of partial discharge (PD) in a transformer insulation system using acoustic signals. The algorithm identifies a bias fault in any of the ultrasonic sensors by computing the probability of having that bias fault given a carefully constructed measurement residual. The constructed measurement residual is a function of the measurement noise and the possible measurement fault. A set of bias hypotheses is assumed and initially given equal alarm probability. It is assumed that only one sensor will acquire a bias at any given time. Once the probability of a hypothesis approaches 1, that hypothesis is declared as the correct hypothesis and the bias associated with the hypothesis is removed from the sensors’ reading. Therefore, this will enable high-accuracy estimation of the location of PD. First, the algorithm is verified in a simulation environment. Subsequently, the accuracy of the proposed algorithm is verified using the experimental results.

A highly diastereoselective annulation strategy for the synthesis of alicyclic ketones from diols and pentamethylacetophenone is described. This process is mediated by a commercially available iridium(III) catalyst, and provides efficient access to a wide range of cyclopentane and cyclohexane products with high levels of stereoselectivity. The origins of diastereoselectivity in the annulation reaction have been explored by a series of control experiments, which provides an explanation for how each stereocentre around the newly forged ring is controlled.