Planar Faces Research Articles

Study of non-stationary cutting processes in power skiving

The paper presents the results of the modelling and study of the cutting process in the cut-in phase during the machining of external gears by the power skiving. The studies were carried out on the basis of the previously developed graphical model of the cut layers and the model of the cutting force as a function of the chip cross-sectional area, the shear strength limit of the workpiece material, and the intensity of plastic deformation during cutting. The regularities of the cutting force in the cut-in phase of gear machining are shown for successive tool revolutions in four passes with a gradual increase in the depth of cut. It is shown that the peak values of the cutting force at the contact between the front face of the cutter and the face plane are two times higher than under the conditions of steady stationary cutting in a preformed gap. At the same time, the amplitude of the cutting force and its average value over the cut-in passes are 1.7–3.7 times and 1.2–1.5 times higher, respectively, than the corresponding values of these parameters for steady state cutting. It is these peak jumps in the cutting force that limit the maximum depth of the cut, number of passes, and axial feed. Based on the data obtained, recommendations were developed to modify the traditional gear cutting scheme in power skiving. It is proposed to use short tool strokes with a low cutting depth along the length of the cut-in path and, after forming a gap in this area, to cut at a full depth to the full height of the gear rim. The possibility of a significant reduction of gear machining time using the proposed scheme of technological operation is demonstrated.

Synthesis, Structure and Catalytic Properties of Hyp3[Ge9Rh]PPh3

In single‐site homogeneous catalysts (SSHoCs) transition metal atoms are incorporated in the surface of a small homoatomic atom cluster. Within this concept the main group element cluster is considered as innocent support material, while the catalysis itself is realised at the transition metal atom. In the case of [Ge9] clusters, both transition metal atoms and the Ge atoms have low oxidation state. Thus improving the synthesis towards transition metal decorated Zintl cluster has become important in the last years, and the catalytic activity of these clusters is of high interest. An optimised one‐step synthetic protocol for Hyp3[Ge9Rh]PPh3 is presented. The product is characterised by NMR spectroscopy, LIFDI/MS and single crystal structure determination. The Rh atom is incorporated in the clusters surface and bridges a deltahedral cluster face, whereby one of the triangular edge opens forming an almost planar face of three Ge and one Rh atom. PPh3 ligand dissociation as well as the catalytic activity in the isomerisation of 1‐hexene and allylbenzene as well as the hydrogenation of those substrates with hydrogen is investigated.

The magnetic gradient tensor of a right circular cylinder: theoretical considerations in the determination of magnetisation direction

This paper investigates the use of the magnetic gradient tensor and its eigenvectors to derive expressions for estimating the direction of magnetisation of a uniformly magnetised right circular vertical cylinder. Expressions for the gradient tensor, the eigenvalues and eigenvectors, the normalised source strength (NSS), and the direction of magnetisation on the axis of a vertical cylinder are shown to be identical in form to those previously derived for a magnetised sphere or dipole. However, the off-axis gradient tensor field of a vertical cylinder is significantly different to that of a magnetic sphere or dipole particularly at low observation heights. These differences lessen with increasing observation height and in more compact pipes. The normalised source strength displays a directional asymmetry in the eigenvector field of the gradient tensor above a pipe which is related to the direction of magnetisation. This azimuthal asymmetry in the NSS results exclusively from the horizontal components of magnetisation, which are perpendicular to the longitudinal face of the vertical cylinder. In contrast, the vertical component of magnetisation is normal to the circular planar face and produces radial symmetry in the NSS. Additionally, the paper details some unusual properties of the NSS which are attributable to non-dipole field components in the gradient tensor field which cause pairs of eigenvectors to interchange directions when ordered by their eigenvalues, as is done when calculating the NSS. This results in spatial discontinuities in the eigenvector fields arising from crossovers in the ordered eigenvalue surfaces which vary with both magnetisation direction and observation height. This phenomenon is not present in a dipole field and thus provides direct evidence of non-dipole field components. Understanding this complexity in the eigenvector field is essential to designing methodologies which can successfully estimate the direction of magnetisation over a uniformly magnetised cylinder. One proposed method based on the peak NSS, uses airborne gradient tensor data to accurately estimate magnetisation direction over a reversely magnetised pipe-like body in the Diavik diamond field of north-western Canada. The results are verified using a full tensor inversion.

Digital Approach Provides Predictability in Increasing the VDO in Erosive Wear: Clinical Technique and 9-Year Follow-Up.

This clinical case describes a digital workflow using face scans and CAD/CAM technology for a full-mouth rehabilitation with increased vertical dimension of occlusion (VDO) with adhesive lithium disilicate restorations after 9 years. A healthy, 46-year-old man displaying severe tooth wear, underwent an extensive full-mouth rehabilitation involving an increase of the VDO through laminate veneers and adhesive partial coverage lithium disilicate restorations. Anatomical landmarks of the face and reference planes were captured using a digital face scanning system. The anatomical position of the maxilla was registered with a transfer device. Digital data sets of the intraoral situation combined with a facial scan enabled precise virtual planning, guiding minimally invasive preparations. Long-term provisional restorations, milled from high-performance polycarbonate, were used to test the novel VDO before the final lithium disilicate restorations were fabricated. This approach provided a time- and cost-efficient treatment solution. No failures were observed at the 9-year follow-up. Utilizing face scans and design software enable a virtual visualization and comprehensive quality control for patients with dental wear, resulting in significant time savings and increased predictability for the dental technician, dentist and patient. The described digital workflow optimizes the planning and implementation of a comprehensive adhesive full-arch rehabilitation with an increase of the VDO. The clinical long-term follow up result of CAD/CAM assisted minimally invasive lithium disilicate restorations after 9 years demonstrates to clinicians a reliable treatment concept for patients with dental wear.

An analytical study of Euler angle and Rodrigues parameter representations of $\mathbb{SO}(3)$ towards describing subsets of ${\mathbb{SO}}(3)$ geometrically and establishing the relations between these

Abstract Descriptions of various subsets of $\mathbb{SO}(3)$ are encountered frequently in robotics, for example, in the context of specifying the orientation workspaces of manipulators. Often, the Cartesian concept of a cuboid is extended into the domain of Euler angles, notwithstanding the fact that the physical implications of this practice are not documented. Motivated by this lacuna in the existing literature, this article focuses on studying sets of rotations described by such cuboids by mapping them to the space of Rodrigues parameters, where a physically meaningful measure of distance from the origin is available and the spherical geometry is intrinsically pertinent. It is established that the planar faces of the said cuboid transform into hyperboloids of one sheet and hence, the cuboid itself maps into a solid of complicated non-convex shape. To quantify the extents of these solids, the largest spheres contained within them are computed analytically. It is expected that this study would help in the process of design and path planning of spatial robots, especially those of parallel architecture, due to a better and quantitative understanding of their orientation workspaces.

High-performance ZnO:CuO composite-based fiber-shaped electrode for non-enzymatic glucose sensing in biological fluids

The growing diabetes epidemic necessitates new glucose sensors, as traditional enzyme-based and planar electrodes face limitations in environmental stability and seamless integration into wearable technology. This research tackles these issues by designing a flexible, enzyme-free glucose sensor utilizing a co-deposited ZnO:CuO (CZ) composite on PET monofilament. This approach improves the tensile strength (55 mm at 2.7 kg.f) and electrical conductance (0.32 S), of the Ni-coated PET fiber, resulting in a strong and reliable sensing platform. The electrode's enlarged electrochemical surface area (0.11 cm2), offer a high density of active sites for glucose interaction, and the synergistic interface significantly enhances both ion and charge mobility. This results in exceptional sensitivity (35.05 mA.cm−2.mM−1), a rapid response (24 s), and a low detection limit (0.15 mM). Durability tests demonstrate that the sensor retains 80% of its sensitivity after 500 bending cycles, making it well-suited for wearable applications. Furthermore, the sensor accurately detects glucose in biological samples, such as saliva, highlighting its potential for non-invasive, real-time glucose monitoring in wearable healthcare systems.

Mathematical framework for the plastic flow of fine-grained solids, from yield to fracture

A newly proposed mathematical approach to plastic flow, holding from yield to fracture, of a fine-grained polycrystal with no voids or cracks is reviewed and applied to commercial steels. The formalism models the polycrystal by a continuum array of random deformable polyhedra leaving no voids between them, which can slide past each other along the shared faces when the shear stress resolved in the face plane exceeds a finite threshold. Grain reshaping for preserving matter continuity induces local forces assumed much weaker than those causing sliding. The relative velocity of adjacent sliding grains is taken as proportional to the local shear stress resolved in the common boundary plane. Explicit equations are derived for the plastic deformation, from yield to fracture. The analysis of mechanical tests of two commercial stainless steels is shown to illustrate how well the theory agrees with practice.

Stress relief and crystal face transition process contribute to the stability of zinc anodes

Zn electrodes are suffering the dendrite growth owing to the enrichment of local space charge, distinct exposed face and residual stress. In this work, we investigated the crystal face properties and stress state of Zn foil through static energy calculations, dynamic crystal growth analysis and finite element simulation of stress states. Then thermal driven is deployed to modify the exposure face and residual stress of Zn foil, aiming for a dendrite-free electrode. The calculation of surface energies and simulation of crystal growth models for different crystal faces indicate that the (001) face can maintain stability during deposition. Inspired by this mechanism, the (101) exposed commercial Zn foil is modified by thermal processing. Firstly, the exposure level of the (001) face increases, though only the peak corresponding to the (002) crystal face is observed, due to the extinction effect of the densely packed plane (001) face. Further, the surface morphology becomes smooth and the stress is released with the progresses time. These stress relief and crystal face transition process strengthen the uniformity of ion distribution, and increase the interface stability during the crystal growth, which reduce the defect sites in the deposition. As a result, the Zn electrode exhibits tiny voltage hysteresis and outstanding cycle stability, which reveals improved electrochemical performance. Additionally, Li and Na can also be improved in exposed crystal faces and release strain energy through similar methods to enhance cycling stability.

Limited Delamination Modifications to the Extended Deep Plane Rhytidectomy: An Anatomical Basis for Improved Outcomes.

Background: This study introduces variations of a limited delamination approach to the deep plane face- and necklift. Objectives: To report surgeons' perceptions of limited delamination deep plane rhytidectomy, define the anatomical basis to support these modifications, and report complication rates. Methods: This retrospective multi-institutional chart review study of patients undergoing a modified classical deep plane face- and necklift. Surgeons' perception of outcomes and self-reported complications were collected. Results: In total, 3964 patients having undergone face- and necklift with six surgeons being included. Most patients were female (87.9%) with an age range of 31-83 years (mean 58 years). Most were primary procedures (2672/3964; 67.4%) with a median follow-up of 425 days (range 21-5470). Preliminary surgeon experience demonstrated increased ease of flap management, improved biomechanics, smaller perceived rates of skin discoloration, and telangiectasia of the skin and lower revisions rate (n = 11; 0.8%). Complication rates were low for hematoma (n = 24; 1.9%) and seroma requiring needle aspiration (n = 26; 2%) and minor infection (n = 18; 1.4%). Conclusions: A multicenter surgeon experience with the limited delamination extended deep plane rhytidectomy is based on anatomical evidence and demonstrates low complication rates and surgeon-perceived improved long-term outcomes. Prospective comparative outcomes of these evolving techniques are warranted.

A slip-line field model for independently characterizing shearing and ploughing effects in metal cutting processes

This study proposes a new slip-line field model to separately characterize the shearing-included cutting process and the pure-plough cutting process. The shear plane and dead metal zone in relation to the shearing effect are modelled by straight slip-lines, while the deformation area in relation to the ploughing effect is treated to have straight boundaries. The boundaries of the dead metal zone and ploughing area are determined by considering tool-workpiece frictional behaviours. The stresses acting on the boundaries of the ploughing area, dead metal zone and shear plane are separately modelled considering the thermal–mechanical coupling effect. Based on the minimum energy principle, the shear angle is originally modelled by following the dynamic requirement of chip flow to balance the forces acting on dead metal zone, shear plane and rake face. By iteratively solving the coupling effect among the temperature, stress and shear angle, the total cutting forces are acquired by integration operation through straight slip-lines. Experiment results and finite element simulations validate the proposed slip-line field model in predicting the shear angle and cutting forces for both micro and regular milling processes.

Extreme roughness reduction and ultrafine quality of innovative dual function material extrusion 3D printer

PurposeThis paper aims to use hybrid manufacturing (HM) to overcome several drawbacks of material extrusion three-dimensional (3D) printers, such as low dimension ranging from 0.2 to 0.5 µm, resulting in a noticeable staircase effect and elevated surface roughness.Design/methodology/approachSubtractive manufacturing (SM) through computer numerical control milling is renowned for its precision and superior surface finish. This study integrates additive manufacturing (AM) and SM into a single material extrusion 3D printer platform, creating a HM system. Two sets of specimens, one exclusively printed and the other subjected to both printing and milling, were assessed for dimension accuracy and surface roughness.FindingsThe outcomes were promising, with postmilling accuracy reaching 99.94%. Significant reductions in surface roughness were observed at 90° (93.4% decrease from 15.598 to 1.030 µm), 45° (89% decrease from 26.727 to 2.946 µm) and the face plane (71% decrease from 12.176 to 3.535 µm).Practical implicationsThe 3D printer was custom-built based on material extrusion and modified with an additional milling tool on the same gantry. An economic evaluation based on cost-manufacturing demonstrated that constructing this dual-function 3D printer costs less than US$560 in materials, offering valuable insights for researchers looking to replicate a similar machine.Originality/valueThe modified general 3D printer platform offered an easy way to postprocessing without removing the workpiece from the bed. This mechanism can reduce the downtime of changing the machine. The proven increased dimension accuracy and reduced surface roughness value increase the value of 3D-printed specimens.

Why Deep Plane Face and Neck Lifting Results in the Maximum Short- and Long-term Results? My Primary Choice for Rhytidectomy in My Practice.

I converted to the extended deep plane facelift and neck lift with a shorter skin flap elevation in the face to achieve a more complete release of the facial ligaments to obtain more mobilization of the skin/superficial musculoaponeurotic system composite flap, and a more medial suspension resulting in improved correction of the midface, nasolabial fold, marionette fold and jowl. Treatment of the deep neck structures allowed for more refinement of the submentum in the deep neck lift procedures as well. In this article, we shall review the surgical technique of the deep plane facelift and neck lift as well as postoperative management pearls, the management of complications from the procedure, and the incorporation of ancillary procedures.

Extended Composite Approach to Deep Plane Face Lifting with Deep Contouring of the Neck and the Nuances of Secondary and Tertiary Facelifting: Principles for Restoration of Natural Anatomy and Aesthetically Attractive Face and Neck Contour.

Patients seek second facelifts either due to dissatisfaction with the primary procedure or years later after continued face and neck aging following successful first surgery. Previous surgical anatomical disruption, deformity of tension and vector, scar formation and skin excision compounded by the proliferation of historical energy-based skin treatments, thread lift procedures, and injectables make revision rhytidectomy a complex process of causal identification and surgical repair. Patients seeking revision due to dissatisfaction with a primary procedure, or worse visible deformity, have a heightened sense of anxiety which necessitates accurate diagnosis, careful examination, comprehensive documentation, and confidence in any planned secondary intervention as well as conservative expectation management. This article outlines the author's approach to identify the challenges posed and successfully perform secondary and revision rhytidectomy using a modified extended deep plane approach.

The Evolution of My Extended SMAS-Biplanar Deep Plane Facelift to a Composite Tissue Deep Plane Face and Neck Lift: Similarities and Differences.

In this article, Dr. Stephen W. Perkins, a seasoned facial plastic surgeon, presents his refined techniques in facelift surgery developed over four decades of practice. His evolution from traditional methods to the current composite tissue deep plane facelift is elucidated. His composite tissue deep plane facelift involves meticulous dissection and repositioning of the superficial musculoaponeurotic system (SMAS) and platysma in the deep plane, as well as incorporating his innovative "Perkins' Kelly clamp anterior platysmaplasty." This technique, refined through years of experience, aims for natural, enduring results, crucially addressing patient concerns such as jowling and neck laxity. Long-term analysis reveals the advantages of Dr. Perkins' technique, particularly in achieving sustained cervicomental angle improvement for over a decade postoperatively. This article underscores the importance of understanding deep plane facelift techniques, distinguishing between different approaches, and tailoring surgical interventions to individual patient characteristics. Dr. Perkins' comprehensive approach, incorporating advancements in surgical technique and meticulous patient care protocols, exemplifies the goal of achieving natural, long-lasting facial rejuvenation.

Interlocking Joints with Multiple Locks: Torsion-Shear Failure Analysis Using Discrete Element and Equilibrium-Based SiDMACIB Models

SiDMACIB (Structurally informed Design of Masonry Assemblages Composed of Interlocking Blocks) is the first numerical model capable of extending the equilibrium problem of limit analysis to interlocking assemblies. Adopting the concave formulation, this model can compute the stress state at the corrugated faces with orthotropic behaviour, such as their combined torsion-shear capacity. Generally speaking, finding the plastic torsion-shear capacity of planar faces shared between conventional blocks is still a fresh topic, while investigating this capacity for interlocking interfaces is particularly rather unexplored. Upon the authors’ previous works that focused on interlocking blocks with a single lock, in this paper, an extension to blocks composed of several locks (multi-lock interfaces) is presented and the SiDMACIB model is upgraded accordingly. For this purpose, the shear-torsion results obtained from the original SiDMACIB formulation are validated and subsequently compared with those derived from distinct element analysis conducted using the 3DEC 7.0 software. Based on this comparison, revisions to the SiDMACIB model are proposed, involving a reduction in the number of locks affecting torsion-shear capacity.

Interactive design of discrete Voss nets and simulation of their rigid foldings

Voss nets are surface parametrizations whose parameter lines follow a conjugate network of geodesics. Their discrete counterparts, so called V-hedra, are flexible quadrilateral meshes with planar faces such that opposite angles at every vertex are equal; by replacing this equality condition with the closely related constraint that opposite angles are supplementary, we get so-called anti-V-hedra. In this paper, we study the problem of constructing and manipulating (anti-)V-hedra. First, we present a V-hedra generator that constructs a modifiable (anti-)V-hedron in a geometrically exact way, from a set of simple conditions already proposed by Sauer in 1970; our generator can compute and visualize the flexion of the (anti-)V-hedron in real time. Second, we present an algorithm for the design and interactive exploration of V-hedra using a handle-based deformation approach; this tool is capable of simulating the one-parametric isometric deformation of an imperfect V-hedron via a quad soup approach. Moreover, we evaluate the performance and accuracy of our tools by applying the V-hedra generator to constraints obtained by numerical optimization. In particular, we use example surfaces that originate from one-dimensional families of smooth Voss surfaces – each spanned by two isothermal conjugate nets – for which an explicit parametrization is given. This allows us to compare the isometric deformation of the smooth target surface with the rigid folding of the optimized (imperfect) V-hedron.

Numerical study of time-dependent stresses in the floor of the stope with powered support

When sections of the powered support are clamped in the stope, one of the ways to move them is to explode the rock under them. In the case when there is outburst-prone sandstone in the seam floor, blasting operations becomes dangerous and it is necessary to study the stress field in the host rocks. In this work, a numerical study of the time-dependent stress field in the floor of the stope with powered support is performed. Distributions of values of geomechanical parameters characterizing the stress field and zones of inelastic deformations at different time steps are given. Graphs of changes in these parameters in the floor of the stope are plotted. The minimum time for unloading sandstone at the place of drilling the hole for explosive charge is calculated. It is shown that in front of the mine face plane, the sandstone in the seam floor is in a uniform compressed state; all components of the stress field are close to unity. However, they start to decrease already 2.5 m before the mine face plane. At the hole drilling site, the maximum stress is 0.77γH, the minimum stress is 0.35γH at a depth of 1 m for given conditions.

Vectorial Analysis of Deep Plane Face and Neck Lift.

The vector of aging and consequently the vector of lift in rhytidectomy has aided surgeons in improving movement of tissues during facial rejuvenation procedures. The goal was to analyze the vector of lift in patients undergoing primary and revisional facelift to achieve proper vectorial lifting. Patients undergoing deep-plane facelift surgery were included for analysis. Intraoperative photographs and measurements were taken of the skin, superficial musculoaponeurotic system (SMAS), and platysmal suture suspension with mastoid crevasse inset. Measurements were compared between patients who were undergoing primary vs secondary surgery, site of lift, age, and gender. Seventy-one patients (90% female, mean age 57.8) with a total of 142 hemifaces were analyzed, 57 (73%) of which were primary and 14 (27%) secondary facelifts. The average vector of SMAS lifting was 70.8°. Females had a more vertical vector than males (71.3° vs 65.4°; P < .01). The average vectors of platysmal and skin lift were 87.0° and 58.2°, respectively. There was intrapatient difference between hemifaces. Despite there being more intersuture disparity in secondary cases than primary cases (16.9° vs 4.5°; P < .05), the mean vector of lifting was similar between them. Proper release of the deep plane helps determine the appropriate vectors of lift, without relying on guidelines based on population averages. Each patient presents with a unique vector required to correct their descent. This technique provides an optimal result by directly suspending against the vectors of greatest descent.

The Nuances and Techniques of Deep Plane Face and Neck Lifting to Maximize the Defined Neck and Jawline and Obtain a Sharp and Beautiful Neck Contour.

This article seeks to expand on our understanding of lifting by utilizing the benefits of deep plane release and repositioning. The deep plane is a more logical and natural approach to lifting of the face and neck, lifting along the natural anatomic glide planes. Deep plane face and neck lifting have demonstrated superior results in the authors' experience with less dependence on ancillary measures such as fat grafting or implantation for midface volumization. The deep plane technique allows for the face and neck to be treated and lifted as a single composite unit, providing a more natural and long-lasting result and less distortion of underlying structures (i.e., mimetic muscle function). Among facelift surgeons, there is still debate and discussion over treatment of various regions including submandibular gland prominence, jowling and deepened prejowl sulcus, anterior digastric prominence, and a low hyoid. In this article, given the opportunity to share personal experiences, we seek to provide additional insight on the merits of deep plane release in rhytidectomy and our novel approaches to avoiding surgical failures.

Study of the effect of macrogeometry of rubbing steel bodies at their point contact on the tribological characteristics of lubricants under boundary lubrication conditions

The effect of the shape of contacting nonconformal elements of friction units that form an initial point contact on the tribological characteristics of lubricants during friction in the boundary lubrication mode. Point contact of rubbing bodies is realized on four-ball friction machines when testing tribological characteristics of lubricants in accordance with Russian GOST 9490–75 and GOST 23.221–84 Standards.However, these tests are carried out with the friction of standard bearing balls and does not allow taking into account the impact of materials of rubbing bodies on the results of the experiment. Therefore, two alternative designs of mandrels were developed, which allow implementation of two friction schemes: «rotating ball clamped in the spindle of the machine – three roller face planes» and «rotating ball — three cylindrical rollers». The load on the friction unit for both friction schemes, as well as in parallel on the mandrel under testing, in which three balls are installed, is the same (108 N), the spindle rotation speed is equal to 1 rpm, duration of testing is 60 min. The diameter of balls used in these experiments was 12.7 mm, and diameters of rollers were 5 and 8 mm, respectively. The material of samples was ShKh-15 tool steel or its 100Cr6 analogue. The designs of mandrels and the dimensions of samples were chosen in such a way that in all cases the contact areas of the experimental samples with the wearing (upper) ball would lie on a circle with a diameter of 7.32 mm. The tests were carried out under dry friction, and in boundary lubricated conditions in a PAO-4 polyalphaolefin oil medium, as well as in the same oil medium with the additives of oleic acid and DF-11 (a solution of zinc dialkyldithiophosphate in a low-viscosity oil). It is shown that the composition of a lubricating medium has a decisive effect on the test results (i.e., on the values of the friction coefficients and on the values of the areas of wear scars), while the geometry of the rubbing bodies, as well as the maximum Hertz stresses in the tribological contact, had a little effect on the antifriction and anti-wear characteristics of oils.