Shear Properties of Earth's Inner Core

Understanding how Earth's inner core (IC) develops and evolves, including fine details of its structure and energy exchange across the boundary with the liquid outer core, helps us constrain its age, relationship with the planetary differentiation, and other significant global events throughout Earth's history, as well as the changing magnetic field. Since its discovery in 1936 and the solidity hypothesis in 1940, Earth's IC has never ceased to inspire geoscientists. However, while there are many seismological observations of compressional waves and normal modes sensitive to the IC's compressional and shear structure, the shear waves that provide direct evidence for the IC's solidity have remained elusive and have been reported in only a few publications. Further advances in the emerging correlation-wavefield paradigm, which explores waveform similarities, may hold the keys to refined measurements of all inner-core shear properties, informing dynamical models and strengthening interpretations of the IC's anisotropic structure and viscosity. ▪ What are the shear properties of the inner core, such as the shear-wave speed, shear modulus, shear attenuation, and shear-wave anisotropy? Can the shear properties be measured seismologically and confirmed experimentally? Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

On the probability of formation of intermetallic compounds in dissimilar welded joints obtained by friction stir welding

The article describes the mechanisms and causes of the occurrence of intermetallic phases during friction stir welding of dissimilar joints. The nucleation and growth of intermetallic phases for a pair of dissimilar metals to be welded under comparatively favorable time and temperature conditions of the FSW is facilitated by the atomic-vacancy environment, which is responsible for the continuous atomic-structural bond and mass transfer of accumulated atoms in local regions of the welded joint with an equiaxial grain lamella-shear structure of the welded core. compounds with a concentration close to critical, combined with others in a superplastic state. In the process of forming a welded joint under the influence of a moving and rotating welding tool, the lamellae are subjected to bending and torsional stresses with simultaneous tension, causing them to generate point defects and especially a large number of various types of dislocations, triggering the formation of edge dislocations in the lamellae, which are lined up in the process into dislocation walls, dividing lamella grains into separate fragmentary subgrain boundaries, along which the processes of fragmentation and dispersion develop. This phenomenon is explained by the fact that the processes of fragmentation and dispersion of IMP lead to the composition of the nugget of the welded joint by fragments, often nano-sized fragments of various configurations, which act as hardeners of the weld nugget matrix.

Optimization of hydrogen-ion storage performance of tungsten trioxide nanowires by niobium doping

The transport and storage of ions within solid state structures is a fundamental limitation for fabricate more advanced electrochemical energy storage, memristor, and electrochromic devices. Crystallographic shear structure can be induced in the tungsten bronze structures composed of corner-sharing WO6 octahedra by the addition of edge-sharing NbO6 octahedra, which might provide more storage sites and more convenient transport channels for external ions such as hydrogen ions and alkali metal ions. Here, we show that Nb2O5·15WO3 nanowires with long length-diameter ratio, smooth surface, and uniform diameter have been successfully synthesized by a simple hydrothermal method. The Nb2O5·15WO3 nanowires do exhibit more advantages over h-WO3 nanowires in electrochemical hydrogen ion storage such as smaller polarization, larger capacity(71 mAh/g, at 10C, 1C = 100 mA/g), better cycle performance (remain at 99% of the initial capacity after 200 cycles at 100C) and faster H+ diffusion kinetics. Therefore, complex niobium tungsten oxide nanowires might offer great promise for the next generation of hydrogen ion batteries.

Study on Tuned Mass Damper Use in High-Rise Building

Current styles in the construction industry demand tall and light buildings, which are also flexible and low-cost. This increases the chances of failure and problems from the point of view of usability. Many modern methods are available to reduce structural vibration, with many vibration control strategies, the idea of using the new TMD. This study was conducted to study the efficacy of using TMD in controlling structural movement. Initially a numerical algorithm was developed to investigate the response of a shear structure containing TMD. Next another numerical algorithm was developed to investigate the response of an independent 2D model programmed with TMD. Three slow loading methods used. The first was a sinusoidal upload, the second was in line with the corresponding timeline according to IS-1894 (Part -1): 2002 with 5% erosion (PGA = 1g) and the third was 1940 El Centro Earthquake Record (PGA) = 0.313g). From research it has been found that TMD can be used effectively to control building vibrations. TMD worked best when the softness of the structure was low. Gradually increase the magnitude of the effects of TMD on the gradual decline in the response to structural migration. Keywords: Harmonic absorber, viscous damper, crankshaft torsional damper, kinetic energy,

Shear-structure MoNb6O18 as New Anode for Lithium Ion Batteries

Owing to their high theoretical capacities, safety operate voltage, unique tunnel structural features for fast lithium ion transfer and structural stability, niobium-based oxides are regarded as promising candidate anode materials...

A Niobium Oxide with Shear Structure and Planar Defects for High-Power Lithium Ion Batteries

The development of anode materials with high-rate capability is critical to high-power lithium batteries. T-Nb2O5 has been widely reported to exhibit pseudocapacitive behavior and fast lithium storage capability. However, the...

Research on Seismic Design of High-Rise Buildings Based on Framed-Shear Structural System

Under the rapidly advancing economic trends, people’s requirements for the functionality and architectural artistry of high-rise structures are constantly increasing, and in order to meet such modern requirements, it is necessary to diversify the functions of high-rise buildings and complicate the building form. At present, the main structural systems of high-rise buildings are: frame structure, shear wall structure, frame shear structure, and tube structure. Different structural systems determine the size of the load-bearing capacity, lateral stiffness, and seismic performance, as well as the amount of material used and the cost. This project is mainly concerned with the seismic design of frame shear structural systems, which are widely used today.

Towards the Development of an Operational Digital Twin

A digital twin is a powerful new concept in computational modelling that aims to produce a one-to-one mapping of a physical structure, operating in a specific context, into the digital domain. The development of a digital twin provides clear benefits in improved predictive performance and in aiding robust decision making for operators and asset managers. One key feature of a digital twin is the ability to improve the predictive performance over time, via improvements of the digital twin. An important secondary function is the ability to inform the user when predictive performance will be poor. If regions of poor performance are identified, the digital twin must offer a course of action for improving its predictive capabilities. In this paper three sources of improvement are investigated; (i) better estimates of the model parameters, (ii) adding/updating a data-based component to model unknown physics, and (iii) the addition of more physics-based modelling into the digital twin. These three courses of actions (along with taking no further action) are investigated through a probabilistic modelling approach, where the confidence of the current digital twin is used to inform when an action is required. In addition to addressing how a digital twin targets improvement in predictive performance, this paper also considers the implications of utilising a digital twin in a control context, particularly when the digital twin identifies poor performance of the underlying modelling assumptions. The framework is applied to a three-storey shear structure, where the objective is to construct a digital twin that predicts the acceleration response at each of the three floors given an unknown (and hence, unmodelled) structural state, caused by a contact nonlinearity between the upper two floors. This is intended to represent a realistic challenge for a digital twin, the case where the physical twin will degrade with age and the digital twin will have to make predictions in the presence of unforeseen physics at the time of the original model development phase.

Multi-taper method based substructure identification for shear structures

Quickly and accurately identifying structural status after natural disasters plays crucial roles in disaster rescue. Previously, the authors developed a substructure identification method for shear structures, which uses the frequency responses of short structural acceleration responses to estimate structural parameters inductively. However, the numerical studies found that the method could only provide moderately accurate results. In this paper, a thorough uncertainty analysis is performed to reveal the key factors that influence its identification accuracy. Based on these results, a new substructure method is proposed herein, which utilizes the cross power spectrum densities of structural responses, estimated by the multi-taper method, to formulate substructure identification problems. The error analysis is also conducted for the multi-taper method based method, explaining why this method can significantly improve identification accuracy, compared with the frequency response based method. Moreover, although the multi-taper method based method is originally derived based on stationary structural responses, a further analysis shows that it can be extended to non-stationary responses, greatly broadening the method’s application range. Finally, the simulation study of a 20-story shear structure and the shake table tests on a three-story bench-scaled structure are conducted, which verified that the proposed multi-taper method based method indeed significantly improves the substructure identification accuracy.