A Soft Computing-Based Analysis of Cutting Rate and Recast Layer Thickness for AZ31 Alloy on WEDM Using RSM-MOPSO

In the present research, the AZ31 alloy is machined by wire-cut electric discharge machining (WEDM). The experiments were designed according to the Box-Behnken design (BBD) of response surface methodology (RSM). The input process variables, namely servo feed (SF), pulse on-time (Ton), servo voltage (SV), and pulse off-time (Toff), were planned by BBD, and experiments were performed to investigate the cutting rate (CR) and recast layer thickness (RCL). The analysis of variance (ANOVA) was performed to determine the influence of machining variables on response characteristics. The empirical models developed for CR and RCL were solved using Multi-Objective Particle Swarm Optimization (MOPSO). Pareto optimal front is used for the collective optimization of CR and RCL. The optimal solution suggested by the hybrid approach of RSM-MOPSO is further verified using a confirmation test on the random setting indicated by the hybrid algorithm. It is found that the minimum RCL (6.34 µm) is obtained at SF: 1700; SV: 51 V; Toff: 10.5 µs; and Ton: 0.5 µs. However, maximum CR (3.18 m/min) is predicted at SF: 1900; SV: 40 V; Toff: 7 µs; and Ton: 0.9 µs. The error percentage of ±5.3% between the experimental results and predicted solutions confirms the suitability of the proposed hybrid approach for WEDM of AZ31.

Comparisons of flow dynamics of dual-blade to single-blade beveled-tip vitreous cutters

Introduction: To compare the flow dynamics of the dual-blade to the single-blade beveled-tip vitreous cutters. Methods: The aspiration rates of balanced salt solution (BSS) and swine vitreous were measured for the 25-gauge and 27-gauge dual- and single-blade vitreous cutters. The flow dynamics of BSS and diluted vitreous mixed with fluorescent polymer at the maximal cutting rates and the reflux of BSS were measured in images obtained by a high-speed camera. The distal end of the cutter was defined as the head end. Results: The aspiration rates of BSS and vitreous by the 25- and 27-gauge dual-blade cutters were significantly higher than those of both single-blade cutters at the maximal cutting rate (all P≤0.01). The mean aspiration flow of BSS in front of the port from a lateral view was significantly faster for both dual-blade cutters than for both single-blade cutters (P=0.003, P=0.019). The angle of the mean flow of BSS of both dual-blade cutters was from the distal end (P<0.001, P<0.001) but that of the single blade-cutters was from the proximal end. The velocity and angle of the mean reflux flow of both types of cutters were not significantly different. The mean aspiration flow of diluted vitreous was significantly faster for 25-gauge dual-blade cutters with the angle more from the proximal end and 27-gauge dual-blade cutters more from the distal end than both single-blade cutters (P=0.018, P=0.048). Conclusion: The dual-blade beveled-tip vitreous cutters improve the efficiency of the vitrectomy procedures and maintain the distal aspirating flow by the beveled-tip.

Multifractal analysis of ultrasonically machined surfaces of cylindrical quartz crystals: the effect of the abrasive grits

Since synthetic quartz is essential to produce 3-D resonators for numerous applications in precision electronics, in this work the surface topography of cylindrical quartz bars is investigated using the multifractal technique. The cylindrical bars were manufactured with ultrasonic machining using with five SiC grits ranging from 6 to 50 µm. The machined surfaces were initially characterized by contact profilometry and scanning electron microscopy (SEM). The multifractality of the machined surfaces was scrutinized using a box-counting method applied to the images obtained with 500X magnification. The multifractal spectrum indicated that the fractal dimension f(α) and the width of the fractal spectrum Δα are dependent on the grit size, but this dependence is not monotonic. The lowest (negative) value for Δf(α) was found for 25 µm grits indicating that for these grits the lower frequency events (grooves with tens µm width occurring along the USM direction) controls the surface topography much more than high frequency events related to brittle microcracking. The abrasive wear due to the continuous slurry recycling in lateral tool-workpiece interfaces contributed to smooth the groove texture as well as the sharpness of microscopic indentations, which remained observed on the surfaces machined with 50 µm grits. The opposite paths observed for the arithmetical mean deviation of the measured profile (Ra) and Δf(α) parameters with the cutting rate measured for each grit size were valuable to differentiate flat-rough and unlevelled-rough topographies in quartz bars.

Forest industry complex development in Russian Federation regions

The study found that the existing potential of the timber industry complex is not used effectively enough, as evidenced by the low level of wood processing, the development of only 50 % of the declared annual allowable cutting rate, insufficient use of modern technologies for processing wood raw materials, as well as reforestation. The consequence of this is the low share of the timber industry complex in the total volume of production in the regions. Based on the cluster method, the regions of the Russian Federation were grouped in 2010–2019 according to indicators reflecting the availability of resources (forest cover of the territory and the total stock of wood) and the level of their use (the share of the type of economic activity in the total volume of production in the region). The analysis carried out and the results obtained on this basis made it possible to identify the most successful practices for realizing the potential of the timber industry complex, as well as possible directions for the development of the forest industry in the regions of the Russian Federation.

Chip formation processes based on orthogonal processing of polymer composite materials

This paper presents the results of the study of processes occurring in the cutting zone during the processing of polymer composite materials. The research included determining the effects of orthogonal cutting conditions, such as the cutting depth t and cutting rate v, on the tangential component Pz of the cutting force, the length lc of chips, as well as the vibration acceleration W, to clarify the results previously submitted to the scientific community and obtain new data. The study included 12 experiments for different cutting conditions with the cutting depth t varying in the range of 0.1—0.4 mm and the cutting rate — in the range of 6.7—30.2 m/min. The experimental results allowed to determine a range of cutting rates that lead to a low level of elastic deformations of reinforcing fibers. Based on the dynamics of increasing cutting forces in various cutting conditions, tool cutting edge wear, type and length of chips, as well as the vibration acceleration dynamics, we have found that reinforcing composite material fibers accumulate on the tool cutting edge, while elastic fracture of these fibers causes defect formation on the processed surface. The analysis allows giving recommendations on the need for research in the field of abrasive machining with rigid grinding wheels due to the highest hardness of the cutting tool surface, increased machining speed and the possibility of self-sharpening during tool wear.

Theoretical Guarantees for Phylogeny Inference from Single-Cell Lineage Tracing

CRISPR-Cas9 lineage tracing technologies have emerged as a powerful tool for investigating develop-ment in single-cell contexts, but exact reconstruction of the underlying clonal relationships in experiment is plagued by data-related complications. These complications are functions of the experimental parameters in these systems, such as the Cas9 cutting rate, the diversity of indel outcomes, and the rate of missing data. In this paper, we develop two theoretically grounded algorithms for reconstruction of the underlying phylogenetic tree, as well as asymptotic bounds for the number of recording sites necessary for exact recapitulation of the ground truth phylogeny at high probability. In doing so, we explore the relationship between the problem difficulty and the experimental parameters, with implications for experimental design. Lastly, we provide simulations validating these bounds and showing the empirical performance of these algorithms. Overall, this work provides a first theoretical analysis of phylogenetic reconstruction in the CRISPR-Cas9 lineage tracing technology.

Tachyons, tactility, drawing and withdrawing: cinema at the speed of darkness

Longitudinal, quantitative analyses of cinema have established how Hollywood is getting ‘quicker, faster, darker’. While in some senses the ‘intensified continuity’ of contemporary Hollywood narration is a given, the increased darkness of contemporary mainstream cinema remains unexplored – especially with regard to how its speed and its darkness might be inter-related. If to darken the majority of the screen during a film helps to draw our attention to the salient aspects of the image that are better illuminated, then of course this also allows for a faster cutting rate: in principle, there is ‘less’ information for the viewer to have to take in during each shot, meaning that the film can then cut to subsequent images more rapidly. However, there are other ways in which we can interpret this ‘darkening’ of contemporary film narration. For example, it perhaps ties in with a widespread sense of disorientation with regard to the increasingly globalized and connected world that digitization has helped to bring about, and which is equally reflected in the rise of the contemporary ‘mind-game’ or ‘puzzle’ film that is a staple of contemporary Hollywood. The darkness in such films thus gives expression to uncertainty and disorientation. More than this, though, we might use physics to understand the darkness of contemporary cinema in a more ‘meta-physical’ fashion. While it is accepted that light is the ‘fastest’ phenomenon in the known universe, there nonetheless remain unilluminated aspects of the physical universe that defy light as the limit of speed – and which convey the interconnected nature of matter in the contemporary universe. For example, polarized particles have been proven simultaneously to respond to stimuli – at a speed faster than it would take light to travel from one particle to the other, a phenomenon that baffled Albert Einstein, who referred to this process as ‘spooky action at a distance’. Not only does this process suggest what Karen Barad might refer to as the entangled nature of all matter, but it also suggests speeds beyond, or at least different, to that of light. In this essay, then, I shall theorise a ‘speed of darkness’ that can help us to understand how the darkening of contemporary cinema ties in with the interconnected, invisible (‘spooky’) and ultra-rapid nature of the digital world. Perhaps it is not in the light but in the darkness that we can identify the key to understanding contemporary mainstream cinema and the globalized, digital world that produces it.

Evaluation The Performance Of Cvd And Pvd Coated Carbide Tool In Hard Turning Of Aisi-4340 Steel

The work introduced in this proposal tends to the surface unpleasantness and flank wear during hard turning of AISI 4340 steel (33HRC) utilizing CVD (TiCN/Spasm/Al2O3/TiN) multi-facet covered carbide device and PVD (TiCN/Al2O3) covered carbide device. Three variables (cutting rate, feed and profundity of cut) and three level factorial test plans with Taguchi’s L9OA and factual examination of difference were acted to explore the impact of these cutting boundaries on the apparatus and work piece as far as flank wear, and surface harshness. Additionally the examination of these impacts between previously mentioned sorts of apparatuses was finished. The outcomes show that for surface unpleasantness and flank wear, feed and cutting velocity were measurably huge and profundity of cut had least impact on both surface harshness and flank wear. For surface harshness, feed was more huge followed by cutting velocity for the two sorts of devices, while as, for flank wear cutting pace was more huge followed by feed for the two kinds of instruments. Surface completion was estimated in Ra boundary and a decent surface completion was acquired by PVD covered apparatus at low and medium rates, anyway with the speeding up the CVD covered carbide device showed better surface completion. Flank wear was estimated by utilizing optical magnifying instrument and the outcomes show that more wear happened in PVD covered carbide apparatus when contrasted with CVD covered carbide device under same cutting boundaries and natural conditions. Consequently for better surface completion at low and medium velocities PVD covered carbide apparatus is better and for higher paces, CVD covered carbide device is ideal. For low apparatus wear, CVD covered carbide device is liked.

Effect of the Rock Stress on the Water Jet Cutting Performance

Underground quarrying is rarely adopted for granite extraction due to the difficulties in the implementation of traditional technologies (drilling and explosive). As alternative to drilling and explosive, the combination of diamond wire and water jet seems to be the most promising available technology. The cutting performance achievable with the water jet technology depends on the operative parameters, the material characteristics and the state of stress within the rock massif. To assess the effect of the state of stress on the cutting rate, laboratory tests have been performed with an oscillating water jet machine on granite samples subjected to a static load. The stress distribution in the layer of rock to be removed has been evaluated by numerical simulation with the FLAC code (Fast Lagrangian Analysis of Continua). The correlation between the results of the cutting tests and the numerical models of the rock samples has been inferred. Starting from a conceptual model, which theoretically describes the relationship between the cutting rate and the stress, a step function was defined that indicates the ranges of stress where predefined values of the cutting rate are workable.