Anisotropy of a Selective Laser-Melted Ti–6Al–4V Lattice Structure

Selective laser melting (SLM) is a widely adopted additive manufacturing process for the preparation of metallic lattice structures. However, it causes a build-direction-dependent anisotropy of morphologies, microstructures, and mechanical properties, making it difficult to predict the behavior and performance of lattice structures. In this study, tensile samples with different cross-sections and build directions (BDs) were fabricated by SLM. The anisotropic morphology, microstructure, and tensile properties were observed and measured using optical microscopy, scanning electron microscopy, and three-dimensional digital image correlation to determine the effects of the size and BD of SLMed materials. The extracted data were sequentially used to modify the geometric and physical models of the lattice. Body-centered cubic lattice structures were fabricated by SLM, and compression tests were performed to verify the modified compression model. In addition to the BD-related grains, the cross-sectional area of the SLMed sample affects its mechanical properties. The small cross-section makes the microstructure finer because the proportion of the contour path that uses higher power is no longer negligible. The sample with small cross-section has more anisotropy because of the lack of tolerance to heterogeneity and macro defects like roughness. In this study, by analyzing samples with small cross-sections, a model consisting of an isotropic hardening law and Hill’s anisotropic yield function is established to describe the yield and plasticity behavior of the as-built SLMed Ti–6Al–4V lattice. The simulated and experimental data fit very well, verifying the methodology employed in this study.

Stimulated Axion-Like Bipolariton Generation in the Globular Photonic Crystal

Axion is the dark particle introduced to the quantum chromodynamics to solve the strong CP-problem. Because of its dark nature, there are many indirect evidences, but axion itself have not been registered till now. In the paper, we report the observation of dark axion-like particles formed by the polariton coupling in the resonant microcavity of a globular photonic crystal. To overcome the very small cross-section, we use the Bose-Einstein condensation of polaritons into the nearest-to-the-surface microcavity of an opal-like globular photonic crystal. This way, the synchronicity conditions are met and all polaritons have the same wavefunction to be coupled. Moreover, the giant density of states of a Bose-condensate makes polariton coupling not only allowed but stimulated. At the experiment, we observe “Light Shining through a Wall” Primakoff effect which proves dark particles. The additional spectral peak at the unitary polariton line of a maximal transparency of a crystal allows to differ bipolaritons from other particles. The results can be used not only to generate dark particles at a lab, but also to get a laboratory source of an optical-frequency gravitational waves.

What Neutrino Reaction Has a Large Cross-Section?

All reactions that are currently used to detect neutrinos are endothermic (more precisely, endo-energy). They occur at the expense of the energy of neutrino that initiates them. These reactions are characterized by a very small cross-section, which is close in magnitude to the 10−20 barn. Beta decay is an exo-thermal (more precisely, exo-energetic) reaction. Currently, it seems that the entire physical community believes that the beta decay phenomenon occurs completely by accident. However, recent experiments with reactor neutrinos [1, 2] have shown that their flux makes an additional contribution to the beta decay rate. Since beta decay is an exo-energetic reaction, neutrinos catalyze beta-active nuclei without losing own energy (or with a small loss of it). The cross-section of this process is much larger than the cross-section of the endo-energetic interaction of neutrinos with matter. Experimental measurements show that the cross section of reactor neutrinos with 63Ni nuclei is close to 1 barn.

Futures

This chapter assesses the sustainability of the unintended gender parity in Indian elite law firms. What can we expect this accident to produce? And, to the extent we can predict it, how much will this early advantage influence the path dependency these firms are likely to instill in their future genealogy? Of course, without time-series data, predictions about the actual sustainability of this advantage are moot at best. But in considering them through a range of related lenses, the chapter argues that this “accident” could have important implications and extensions, even if only for a small cross-section of the profession. Specifically, it explains that this case of elite Indian legal professionals offers fresh insights not only into the global legal profession, but to larger relationships between mobility, merit, gender, and globalization. While this research appears to focus on a singular occurrence that is best preserved for its own policy extensions, its true value lies not in its own self-extensions, or even in its direct portability, but rather in its ability to inform about the optics and effectiveness of diversity, representation, and inclusion more generally.

STORYING KAITIAKITANGA: Exploring Kaupapa Māori land and water food stories

This article explores the Indigenous principle of kaitiakitanga as it relates to Māori agrifood practices. Our discussion is based on interviews with a small cross-section of Māori in the agrifood sector whose practices are informed by a long-standing appreciation of the interconnected realities of lands, food, people and waterways. We consider how the shared Kaupapa Māori principles underpinning these food practices form part of a wider Kaupapa Māori land, water and food systems approach which we call “Kai Ora”. As is evident in the stories that follow, Kaupapa Māori values are practised in diverse ways by different kaitiaki food producers. For those who participate within any level of Māori food production, this kaupapa-based approach can lead to a range of connected outcomes, such as oranga, tātai hononga, tiaki taiao and ōhanga.

COMBINED FIRMWARE OF DEEP CHANNELS OF VARIABLE CROSS-SECTION

Variants of manufacturing deep channels of different cross-sections in typical details of modern equipment are considered. Most of the methods were created with the participation of the authors of the article and are protected by Russian patents. The results of the research are implemented in production at enterprises of various branches of mechanical engineering. Information is given about the original methods of piercing deep holes with a depth-to-diameter ratio of more than 25:1 by using combined processes with the imposition of high-frequency vibrations and the possibility of obtaining holes of variable cross-section in pressed ceramic and metal workpieces. The production of mating surfaces from small cross-section channels and narrow grooves is considered,which allowed us to offer an original technological process for the erosive chemical production of precision parts. This technology has been used in the manufacture of parts whose traditional processing methods are poorly understood or not feasible.In particular, a new application of combined firmware for obtaining deep holes of small cross-section in metal workpieces obtained by pressing is shown.Typical parts containing deep channels are given, the combined processing of which is the most technologically advanced and allows for a high economic effect.

ELECTROCHEMICAL AND COMBINED TREATMENT IN RHEOLOGICAL FLUID

Questions of search and assignment of working environments are considered, providing stabilization of processes of erosion-chemical and electrochemical dimensional processing at production of deep apertures in metal materials and ceramics. It is shown that the use of rheological fluids with nanoparticles of conductive granules can accelerate the mass transfer of processing products. It is established that when using rheological fluids it is possible to provide the required quality of the surface layer of deep through and blind channels of small cross-section. Experimental works on multielectrode flashing of round and polyhedral channels were carried out, which allowed to develop technological processes of manufacture of the sections of the coupling path for supplying combustible media to a combustion zone.

Before Creating the Concept of the «Ideal» Grain Separator Sieve

The article presents considerations for creating conditions for the intensification of the process of grain separation by geometric features. The review of constructions and the analysis of work of known sieve surfaces from a position of possibility of maintenance of high indicators of technological efficiency at the expense of acceleration of orientation of particles concerning sieve apertures is carried out. It is established that the most favorable orientation conditions are provided by the surfaces formed by longitudinal elements of small cross-section of streamlined shape, which minimize the possibility of placing particles on them in positions of stable equilibrium. Theoretical possibilities of increasing the living cross-sectional areas and live cross-sectional coefficients of sieve canvases without cross-sections are revealed. The dependences of the total width of the longitudinal sections and the coefficient of the living cross section of the sieves on the width of the longitudinal sections for different sieves are given. This makes it possible to visually assess the need to increase the living cross section of the sieves by reducing the width of the longitudinal sections that form them. A significant reduction in the width of the partitions is possible due to the use of new materials - braided cords made of ultra-high molecular weight polyethylene type Spectra / Dyneema, which provide high mechanical strength and wear resistance with «absolute» inextensibility.