The results of the influence of a range of process liquids on the formation of strengthened nanocrystalline structures in the surface layers of steel samples with different carbon content during thermo-deformation treatment are presented. The liquids were mineral oil; mineral oil with active additives containing polymers; water; and an aqueous solution of mineral salts based on magnesium and calcium chlorides. The thickness and hardness of the nanocrystalline layer increased with increasing steel carbon content. The thickness and microhardness of Steel C45 are 230–240 μm and 8.6 GPa, respectively, when using mineral oil with AAP, 110–120 μm and 7.2 GPa, respectively, when using mineral oil alone, and for steel CT80 when using mineral oil, they are 180–200 μm and 9.1 GPa, respectively (C45 and CT80 refers to engineering steels). The process liquid is decomposed into its component chemical elements by the high temperatures and pressures in the contact zone of the tool with the treated surface. It also gives off active hydrogen, which diffuses into the surface layer of the metal and significantly affects its formation. It was established that the greatest thickness and hardness of the layers were obtained after processing pre-hydrogenated samples. The choice of process fluid is critical during thermo-deformation treatment.

Suspended in the atmosphere are millions of tonnes of mineral dust which interacts with weather and climate. Accurate representation of mineral dust in weather models is vital, yet remains challenging. Large scale weather models use high power supercomputers and take hours to complete the forecast. Such computational burden allows them to only include monthly climatological means of mineral dust as input states inhibiting their forecasting accuracy. Here, we introduce DustNet a simple, accurate and super fast forecasting model for 24-hours ahead predictions of aerosol optical depth AOD. DustNet trains in less than 8 minutes and creates predictions in 2 seconds on a desktop computer. Created by DustNet predictions outperform the state-of-the-art physics-based model on coarse 1 x 1 degree resolution at 95 to ground truth satellite data. Our results show DustNet has a potential for fast and accurate AOD forecasting which could transform our understanding of dust impacts on weather patterns.

Boundary layer transition induced by surface roughness elements plays an important role in aerodynamic and aero-thermodynamic design of subsonic/supersonic/hypersonic vehicles. However, the effect of three-dimensional isolated roughness element in the process of promoting/suppressing boundary layer transition is far from being fully understood, particularly in the incompressible laminar flow. In the present study, the laminar-to-turbulent transition induced by a three-dimensional isolated micro-ramp element immersed in an incompressible laminar boundary layer is investigated numerically. The embedded large eddy simulation (ELES) combining the intermittency transition model and the wall-modeled large eddy simulation (WMLES) $ S - \mathrm{\Omega } $ S-Omega model is employed for the first time. Numerical results on the time-averaged/instantaneous flow field and the statistical flow fluctuations are analysed and validated thoroughly by the existing experimental measurements. It is found that the interaction of the secondary and the tertiary streamwise vortices causes a high level of wall shear and an inflectional velocity distribution in the near-wall region. An additional eddy system that develops nonlinearly from the unstable inflectional flow may trigger the boundary layer transition. The present study validates that the ELES combined with the WMLES $ S - \mathrm{\Omega } $ S-Omega model is an efficient simulation tool for industrial wall-bounded flows allowing effective compromise between flexibility, cost, and accuracy.

We discuss the problem of the quantization and dynamic evolution of a scalar free field in the interior of a Schwarzschild black hole. A unitary approach to the dynamics of the quantized field is proposed: a time-dependent Hamiltonian governing the Heisenberg equations is derived. It is found that the system is represented by a set of harmonic oscillators coupled via terms corresponding to the creation and annihilation of pairs of particles and that the symmetry properties of the spacetime, homogeneity and isotropy are obeyed by the coupling terms in the Hamiltonian. It is shown that Heisenberg equations for annihilation and creation operators are transformed into ordinary differential equations for appropriate Bogolyubov coefficients. Such a formulation leads to a general question concerning the possibility of gravitationally driven instability, that is however excluded in this case.

Crank presses belong to the class of machines in which the payload (stamping force) acts for a short period of time at the end of the working stroke. Since the power of a force is the product of the force times the speed, it is possible to reduce the power of a specific force only by reducing the speed of the point of action of the force. The kinematic characteristics of slider-crank mechanisms (SCMs), which are the main mechanism of crank presses, are qualitatively the same and cannot be changed. The speed of the slider, as a working body, is the most influenced by the rotation frequency and the crank's length. However, reducing the frequency of rotation leads to a decrease in the productivity of the press, and a decrease in the length of the crank is limited by the design possibilities and technological process of stamping. The purpose of this work is to reduce the kinetic power of the main working mechanism of crank presses by redistributing the start-up and run-out phases of the working body and designing the corresponding structural diagram of the SCM. Research methodology. A non-standard approach to reducing the kinetic power of crank presses is proposed. It is suggested to change the distribution of the run-up and run-out phases of the slider (punch) in order to reduce its speed in the range of the punching force to achieve this. To change the run-up and run-out time, a slider-crank mechanism with a programmable change in the length of the crank with a fixed cam is proposed. As a result of this research, an asymmetric cosine law of the movement of the slide was analyzed and it was synthesized into a variable crank length that ensures the movement of the slider according to the determined law. As far as we aware this is the first research that has been carried out on crank presses with the aim of reducing the kinetic power without reducing the value of the stamping force and press productivity. For a given punching force and an asymmetric cosine law for the punch motion, the kinetic power of the press is reduced by 31.4%. This will reduce the mass and/or radius of the flywheel. A list of planned further studies is: the influence of different functions for punch motion, functions for changing the punching force, and an investigation of the value and position of the force interval on the kinetic power of the press.

During the TDT of 41Cr4 steel specimens, a uniformly reinforced white layer with a nano-crystalline structure is formed in the surface layers. The wear resistance of sliding friction without the lubrication of a pair of steel 41Cr4—grey cast iron EN-GJL-200 (EN) under the face-to-face (“ring-ring”) scheme has been studied. It is revealed that when the sliding velocity changes from 0.25 m/s to 4 m/s and the unit load changes from 0.2 MPa to 1.0 MPa, a pair with a reinforced surface layer on 41Cr4 steel specimens and unreinforced specimens of EN-GJL-200 (EN) grey cast iron has a higher wear resistance than an unreinforced pair. The wear resistance increases for both reinforced and not reinforced specimens operating in a friction pair.

The possibility of on-horizon collisions of unbounded energy in the case of an extreme Kerr black hole is known as the BSW effect. It is also a widely accepted point of view that the energy collision of two identical particles of mass m near the horizon of a Schwarzschild black hole is limited to a value of 25 m. We show that there are two possible scenarios for unbounded energy collisions both for the exterior and for the interior of spherically symmetric black holes. Similar scenarios are found for axially symmetric black holes. It is shown that divergent (infinite) energy on-(inner)horizon collisions are excluded due to the anisotropic character of the dynamics of black hole interiors.

An electrocardiogram (ECG) pattern classification method has been proposed to distinguish heart conditions such as arrhythmia (ARR) and congestive heart failure (CHF) from normal sinus rhythms (NSR) using deep convolutional neural networks (CNNs) by converting the ECG signals into RGB images. The results demonstrate an increase in diagnostic accuracy from 90.63% to 94.12% using a pretrained CNN model by utilising additional data from the second lead of the ECG.

Osteoarthritis is a major cause of mobility problems in older people and is a particular problem in former sportspeople. The objective of this study was to develop and characterise a new system for the detection, monitoring and analysis of acoustic emissions from knee joints. 15 adult volunteers participated in the study. The participants performed six sets of three sit-stand-sit cycles. Reflective markers were placed at specific body landmarks recorded by 3D cameras. The exercise was performed with one foot on a force platform. A sensitive condenser microphone with a wide frequency response was connected to a dedicated acoustic analysis unit. Preliminary results provide clear acoustic signals showing a distinctive sequence of impulse-decay forms occurring naturally during each sit-stand-sit cycle. There are distinct differences between the acoustic signals emitted from younger healthy knees and those from aged knees. This work demonstrates the potential for this system to be used as an indication of the state of health of a human knee during movement.

The technique for synthesis of poly (methyl methacrylate) (PMMA) by atom transfer radical polymerization has been strengthened by using graphene nanoplatelets (GNPs) to enhance the elastic properties of the polymer. In order to improve practical, economical and mechanical performance, the requirements for effective implementation of production control as a smart bulk polymer nanocomposite were determined for cost-effective bulk production. Three-dimensional inspection (using an ultrasound interrogation method for the whole volume under test) confirmed the synthesis of the nanocomposite to be free of agglomeration and bubbles. As a result of this elimination of defects, an enhancement in compressive strength of 42.7% was achieved and the Rockwell hardness was increased by 19.9% through the addition of GNPs at 2 wt% by mass. The deformation and mechanical failure properties have been characterized in the mechanical enhancement of the polymer nanocomposite. Elastic parameters determined using ultrasound testing identified that changes in the structural features following the addition of these GNPs were uniquely connected to the enhancements in these elastic parameters (such as Young's modulus, Poisson's ratio, shear modulus, and microhardness) of the PMMA/GNPs nanocomposite.

We introduce here a new index of diversity based on consideration of reasonable propositions that such an index should have in order to represent diversity. The behaviour of the index is compared with that of the Gini-Simpson diversity index, and is found to predict more realistic values of diversity for small communities, in particular when each species is equally represented and for small communities. The index correctly provides a measure of true diversity that is equal to the species richness across all values of species and organism numbers when all species are equally represented, as well as Hill's more stringent 'doubling' criterion when they are not. In addition, a new graphical interpretation is introduced that permits a straightforward visual comparison of pairs of indices across a wide range within a parameter space based on species and organism numbers.

One can question the relationship between the symmetries of the exterior and interior of black holes with an isotropic and static exterior. This question is justified by the variety of recent findings indicating substantial or even dramatic differences in the properties of the exterior and interior of isotropic, static black holes. By invoking some of these findings related to a variety of the thought experiments with freely falling or uniformly accelerated test particles, one can establish the dynamic properties of the interior, which turn out to be equivalent to anisotropic cosmology, simultaneously expanding and contracting, albeit in different directions. In order to illustrate the comparison between the symmetry of the exterior vs. the interior, we apply conventional t, r, θ, φ coordinates to both of these ranges, although on the horizon(s) they display singular behavior. Using a simple approach based on co-moving and freely falling observers, the dynamics of the cylindrically shaped interior are explored. That enables us to present schematic snapshots of the interior of a Schwarzschild black hole, expanding along its cylindrical axis and contracting along its spherical base, as well as the interior of a Reissner–Nordström black hole, expanding first and then contracting along the cylindrical axis up to the terminal instant r =r−.

Creep tests of 2D-C/SiC in a wet oxidizing atmosphere were implemented for six samples. The loading process was monitored by acoustic emission (AE). Principal component analysis and a fuzzy clustering algorithm were used to perform pattern recognition of the AE data. All of the AE events were divided into four clusters and labelled as matrix cracking, interfacial damage, fiber breakage and fiber-bundle breakage respectively, according to their physical origin. It was found C/SiC has very scattered rupture lifetimes even under the same test conditions, and the evolution of AE events corresponding to fiber failure is quite different. With increasing rupture lifetime, the AE energy of fiber-bundle breakage is higher, while the number of these events is less. Thus, it is concluded that local oxidation and damage development is the controlling failure mechanism for short-lived specimens and uniform oxidation and damage development is the controlling failure mechanism for long-lived specimens.

The supermassive black hole located in the galaxy M87 (BH M87) is four times larger than our solar system. If it is spherically symmetric, then a capsule free falling from a distance of 1 light year would cross BH M87's event horizon within some tens of years. Continuing that journey, any unfortunate astronomer traveling within the capsule would remain alive for a few further tens of hours; if the capsule were equipped with a powerful engine and could slow down, their lifetime inside the horizon beyond "the gates of Hell" would be slightly extended. How is this so? What are the other properties of the interior of BH M87? Maintaining the assumption of spherical symmetry of the exterior of BH M87, we briefly discuss some simple but intriguing properties of its interior, a region that turns out to be highly anisotropic, both expanding and contracting at the same time.

Three types of phenomena occurring on both sides of the event horizon of spherically symmetric black holes are analyzed and discussed here. These phenomena are: a light ray orbiting a photon sphere and its analogue, the motion of a uniformly accelerated massive particle and a generalized Doppler effect. The results illustrate how the anisotropic dynamics of the interior of black holes, distinct in the cases both with and without an additional internal horizon, affect non-quantum behaviour.

Dropped-weight impact tests were carried out to investigate the coating damage behavior of SiC coated plain-woven C/SiC composites under low velocity impact. The oxidation performance after impact was evaluated in a wet oxygen environment. The relationships between coating damage area, oxidizing weight loss and the flexural strength after oxidation with the impact energy were analyzed. It was concluded from the test results that 0.5 J was the impact energy corresponding to damage initiation of the coating, where the oxidation loss was 2.49% and the strength retention ratio was 94.92%, almost the same as the untreated coating. Between 0.5 J and 2 J, the weight loss of oxidation increased with impact energy, and the oxidation mechanism gradually changed from a diffusion-controlled local oxidation to a reaction-controlled uniform oxidation. When the impact energy was larger than 2 J, although the coating damage still increased with impact energy, weight loss and residual flexural strength remained almost constant. The residual strength remaining was no more than 8% of the non-oxidized C/SiC, indicating that the coating totally loses its anti-oxidation function.

The continual development of technology represents a challenge when preparing engineering students for future employment. At the same time, the way students interact in everyday life is evolving: their extra-curricular life is filled with an enormous amount of stimulus, from online data to rich Web-based social interaction. This chapter provides an assessment of various learning technology-driven methods for enhancing both teaching and learning in the science and engineering disciplines. It describes the past, present, and future drivers for the implementation of hands-on teaching methods, incorporating industry standard software and hardware and the evolution of learning experiments into all-encompassing online environments that include socializing, learning, entertainment, and any other aspect of student life when studying science and engineering.

We present the results of an investigation of the speed of a radially infalling test particle crossing the event horizon of a black hole within a Schwarzschild spacetime. One finds that the speed as measured by a special class of observers, at rest outside the horizon and static inside the horizon, increases when the test particle approaches the horizon but decreases inside the horizon. The corresponding situation regarding black holes possessing both outer and inner horizons is also briefly discussed.

Large black holes of millions of solar masses are known to be present in the centre of galaxies. Their mass is negligible compared to the mass of the luminous matter, but their entropy far exceeds the entropy of the latter by 10 orders of magnitude. Strong gravitational fields make them 'black'—but at the same time, they cause them to emit radiation—so they are not 'dark'. What is the meaning of their borders that may only be crossed once and that leads to the information paradox and what are the properties of their interiors? In discussing these and related questions (is it possible that the volume of a black hole might be infinite?), we uncover the unexpected meaning of the term 'strong gravity'.