Analysis of the General Tool Life Function of Cutting Tools by Application of the Catastrophe-Theory

Production technology planning requires information on tool life T and its relation to cutting speed v. As the Taylor formula often cannot be linearized on an lg-lg scale, a general tool life function has been developed for describing a v-T function with a convex-concave part. Using catastrophe theory, an analogy is established between the general tool life function and the cusp catastrophe, allowing topological mapping of the general v-T function. Results were verified by machinability tests in the turning of C35 and C60 conventional and specially deoxidized C-steels during steelmaking. It was found that in the convex-concave section of this function, 2–3 cutting speeds can be selected for a given tool life, which is advantageous for harmonizing tool changes in multi-operation technology.

Research on the Contour Capture Algorithm of the Key Action of Dance with Computer-Aided

In order to solve the problem that the current key dance motion contour capture algorithm cannot effectively capture the concave part of the key dance motion contour, which leads to large contour capture error and long response time, a computer-aided key dance motion contour capture algorithm is proposed. The action sequence without background is obtained from the dance video, and the action sequence is optimized to reduce the interference of contour capture. Algorithm tracks the posture change of the object in the dance action sequence, determines the contour capture area, and completes the contour capture of the dance key action. Experimental results show that the proposed method can effectively improve the capture accuracy and shorten the response time.

ВИВЧЕННЯ ПРОЦЕСУ ОДНОВІСНОГО РОЗТЯГУ ТРИКОТАЖУ ПЕРЕПЛЕТЕННЯ ЛАСТИК РІЗНИХ РАПОРТІВ

Study of the process of deformation of rib knits, which occurs due to the application of tensile forces in the course direction. Methodology. During the study, methods of theoretical analysis, a camera, a stretching frame, Microsoft Excel software and Autodesk AutoCAD were used. Findings. For producing rib knit samples, a 10th class flat-bed knitting machine PVRK was used. Samples of knitwear were made with repeatable unit patterns of 1x1, 2x2, 3x3, 4x4, 5x5 and 6x6 from bamboo yarn of linear density 29x2 tex, woolen yarn 32x2 tex, half-woolen yarn 31x2 tex and Polyacrylonitrile yarn 32x2 tex. To carry out uniaxial stretching of knitted fabric samples along the line of stitch rows, a stretching frame was used. After fixing the opposite ends of the sample on the needle set of the frame holders, the distance between them gradually increased with an interval of 20 mm. At each stage of stretching, the samples were photographed together with a calibration ruler. Sample photos imported into Autodesk AutoCAD software. After calibration, for each state of stretching of the sample, such characteristics were determined as: the average value of the width of the repeatable unit pattern, the average value of the width of the convex part of the pattern, as well as the visible section of its concave part. The study showed that at the first stages of stretching, there is a mutual displacement of the sections of the pattern, belonging to different layers of knitwear and a decrease in the twisting of the sections of the smooth surface. Further application of the tensile force leads to a more uniform deformation of the ivestigated structural parts of the pattern. Scientific novelty. The change in the geometric characteristics of rib knits with various repeatable units patterns made from various types of raw materials is experimentally determined. Practical value. The characteristics of knitwear, obtained in the course of the study, were used to form a database necessary for the construction of three-dimensional models of rib knits with bamboo, woolen, semi-woolen, and polyacrylonitrile yarns.

Development of pre-molded internal thread on composite tubes

Premolded internal threads on composite tubes were developed. The composite tubes with threads on both ends were made using a mandrel with a male thread. The threads can be applied to struts with adjustable end fits and composite pressure vessels with threaded caps that enable disassembly for inspection and repair. Carbon fiber-reinforced plastic (CFRP) prepregs were laid up on a mandrel, wrapped with shrink tape, and cured in an oven. The threads were built-in, without using machine cutting, and the fibers on the thread were continuous through the thread and tubes for high strength. The thread was alternately rounded, convex, and concave in shape to enable CFRP prepregs to be laid up. Two types of specimen were made and tested. The layup sequence of specimen A was [0/h/90/h/0/h(1/2)]s, and that of specimen B was [0/h/90/h/90/h/0/h/90/h/90/h/90/h/90/h/0/h/90/90/0], where “h” denotes a helical layer along the concave part of the threads. The relation between load and strain is nonlinear because of the rounded shape of the threads; however, a simple and closed form analytical model was able to predict the strength of the threads and design of the threads. The model was compared with the experimental results. In addition, an application of threads for the pressure vessel of the hybrid rocket motor is also reported. The combustion test proceeded without failure. Visual inspection after the test indicated that the threads and tubes were not damaged, and thus, they can be applied to high-pressure and high-temperature rocket motors.

Two new species of Cantharis Linnaeus, 1758 from Baltic amber

Two new species of soldier beetles (Coleoptera, Cantharidae) from the Priabonian deposits in Yantarny, Russia (Baltic amber) are described. Cantharis crisantha sp. nov. is characterized by its relatively small body size, laterally rounded prothorax, and simple claws with a small basal tooth. Of particular interest, this specimen has its aedeagus extruded—a feature described for the first time in a representative of the genus Cantharis found in amber, and something rarely seen in all known fossil species of the Cantharidae family. The second described species, Cantharis raeorum sp. nov., is characterized by a pronotum with straight sides and a transverse and concave part near the posterior margin. The species are compared with earlier reported fossil Cantharis.

Polyhedral DC Decomposition and DCA Optimization of Piecewise Linear Functions

For piecewise linear functions f : R n ↦ R we show how their abs-linear representation can be extended to yield simultaneously their decomposition into a convex f ˇ and a concave part f ^ , including a pair of generalized gradients g ˇ ∈ R n ∋ g ^ . The latter satisfy strict chain rules and can be computed in the reverse mode of algorithmic differentiation, at a small multiple of the cost of evaluating f itself. It is shown how f ˇ and f ^ can be expressed as a single maximum and a single minimum of affine functions, respectively. The two subgradients g ˇ and − g ^ are then used to drive DCA algorithms, where the (convex) inner problem can be solved in finitely many steps, e.g., by a Simplex variant or the true steepest descent method. Using a reflection technique to update the gradients of the concave part, one can ensure finite convergence to a local minimizer of f, provided the Linear Independence Kink Qualification holds. For piecewise smooth objectives the approach can be used as an inner method for successive piecewise linearization.

DEMONSTRATION OF THE HUMAN HAIR FOLLICLE MAGNETORECEPTION OF BIOMAGNETISM RADIATED BY THE CONCAVE PART OF THE HUMAN HAND

Biological material has been documented to produce an external magnetic field that radiates out. There have been several papers documenting the magnetic fields produced by steady currents in the body. The most notable was published in 1980 by Cohen et al. where the human hair follicle was used as sentinel and biophysically evaluated via sophisticated equipment such as a double planar Superconducting Quantum Interference Devices (SQUID). Most recently, in 2019 Cohen’s work was duplicated by Khan,S by also using double-planar gladiometers. Of interest to this manuscript is that since the introduction of anovel optical microscopy method in 2016 by Scherlag BJ et al is that numerous papers have been introduced in the literature now identifying intrinsic biomagnetic properties of the follicle such as penetration through glass barriers. In this manuscript, a concept of biomagnetic fields by the concave part of the human hand transferring energy to hair follicles is introduced, this was accomplished by using a novel optical microscopy method, in other words, the hair follicle is not limited to radiate out biomagnetism; but also, to receive externally radiated biomagnetic fields from a body part. This magneto receptive property is herein introduced.

Performance Analysis of Savonius-Style Wind Turbines Under Concentrated and Oriented Jets

With the rapid growth of renewable energy sector, vertical axis wind turbines are finding their applications in the small-scale distributed wind energy system, particularly in rural areas. These turbines are simple in construction and easy to install with comparatively lower cost. However, the efficiency of these turbines is not competitive to that of horizontal axis wind turbines. In this paper, an attempt has been made to improve the efficiency of a Savonius-style vertical axis wind turbine under concentrated and oriented jets through installation of deflectors at different positions ahead of the turbine. The aim is to make the major portion of the flow to be incident on the concave part of the blades. Experiments are conducted in a low speed wind tunnel with an open test section facility. For all the experiments, the wind speed in the tunnel is kept constant at 6.2 m/s. The mechanical loads are varied to analyze the performance of the turbine at various tip speed ratios. In each case, both power and torque coefficients are calculated in order to estimate the performance indices of the turbine. Moreover, a suitable operating range of this turbine is specified. The present investigation demonstrates that with the installation of deflectors, the performance of the Savonius-style wind turbines can be sufficiently improved under concentrated and oriented jets. The peak power coefficient of 0.32 is achieved with an optimized position of the deflectors in front of both the advancing and returning blades.

Thickness of immediate dentin sealing materials and its effect on the fracture load of a reinforced all-ceramic crown

ABSTRACT Objectives: The objective of this study is to evaluate, in vitro, the thickness of immediate dentin sealing (IDS) materials on full crown preparations and its effect on the fracture load of a reinforced all-ceramic crown. Materials and Methods: Sixty premolars received full crown preparation and were divided into the following groups according to the IDS technique: G1-control; G2-Clearfil SE Bond; and G3-Clearfil SE Bond and Protect Liner F. After the impressions were taken, the preparations were temporized with acrylic resin crowns. IPS empress 2 restorations were fabricated and later cemented on the preparations with Panavia F. 10 specimens from each group were submitted to fracture load testing. The other 10 specimens were sectioned buccolingually before the thicknesses of Panavia F, Clearfil SE Bond and Protect Liner F were measured in 10 different positions using a microscope. Results: According to analysis of variance and Tukey′s test, the fracture load of Group 3 (1300 N) was significantly higher than that of Group 1 (1001 N) (P < 0.01). Group 2 (1189 N) was not significantly different from Groups 1 and 3. The higher thickness of Clearfil SE Bond was obtained in the concave part of the preparation. Protect Liner F presented a more uniform range of values at different positions. The thickness of Panavia F was higher in the occlusal portion of the preparation. Conclusions: The film thickness formed by the IDS materials is influenced by the position under the crown, suggesting its potential to increase the fracture load of the IPS empress 2 ceramic crowns.