Journal articles: 'Conical liners'

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Alshwawra, Ahmad, Florian Pohlmann-Tasche, Frederik Stelljes, and Friedrich Dinkelacker. "Enhancing the Geometrical Performance Using Initially Conical Cylinder Liner in Internal Combustion Engines—A Numerical Study." Applied Sciences 10, no. 11 (2020): 3705. http://dx.doi.org/10.3390/app10113705.

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Reducing friction is an important aspect to increase the efficiency of internal combustion engines (ICE). The majority of frictional losses in engines are related to both the piston skirt and piston ring–cylinder liner (PRCL) arrangement. We studied the enhancement of the conformation of the PRCL arrangement based on the assumption that a suitable conical liner in its cold state may deform into a liner with nearly straight parallel walls in the fired state due to the impact of mechanical and thermal stresses. Combining the initially conical shape with a noncircular cross section will bring the liner even closer to the perfect cylindrical shape in the fired state. Hence, a significant friction reduction can be expected. For the investigation, the numerical method was first developed to simulate the liner deformation with advanced finite element methods. This was validated with given experimental data of the deformation for a gasoline engine in its fired state. In the next step, initially conically and/or elliptically shaped liners were investigated for their deformation between the cold and fired state. It was found that, for liners being both conical and elliptical in their cold state, a significant increase of straightness, parallelism, and roundness was reached in the fired state. The combined elliptical-conical liner led to a reduced straightness error by more than 50% compared to the cylindrical liner. The parallelism error was reduced by 60% to 70% and the roundness error was reduced between 70% and 80% at different liner positions. These numerical results show interesting potential for the friction reduction in the piston-liner arrangement within internal combustion engines.

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Puente Reyna, Ana Laura, Marcus Jäger, Thilo Floerkemeier, et al. "Backside Wear Analysis of Retrieved Acetabular Liners with a Press-Fit Locking Mechanism in Comparison to Wear Simulation In Vitro." BioMed Research International 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/8687131.

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Backside wear due to micromotion and poor conformity between the liner and its titanium alloy shell may contribute to the high rates of retroacetabular osteolysis and consequent aseptic loosening. The purpose of our study was to understand the wear process on the backside of polyethylene liners from two acetabular cup systems, whose locking mechanism is based on a press-fit cone in combination with a rough titanium conical inner surface on the fixation area. A direct comparison between in vitro wear simulator tests (equivalent to 3 years of use) and retrieved liners (average 13.1 months in situ) was done in order to evaluate the backside wear characteristics and behavior of these systems. Similar wear scores between in vitro tested and retrieved liners were observed. The results showed that this locking mechanism did not significantly produce wear marks at the backside of the polyethylene liners due to micromotion. In all the analyzed liners, the most common wear modes observed were small scratches at the cranial fixation zone directly below the rough titanium inner surface of the shell. It was concluded that most of the wear marks were produced during the insertion and removal of the liner, rather than during its time in situ.

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Ahmed, Mukhtar, Zheng Xiang Huang, A. Q. Malik, Xu Dong Zu, Qiang Qiang Xiao, and Munir Ahmed. "Penetration Performance of Shaped Charge Jets Using Insensitive Munition: Simulative and Experimental Studies." Advanced Materials Research 1102 (May 2015): 119–23. http://dx.doi.org/10.4028/www.scientific.net/amr.1102.119.

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The simulation and experimental studies of the Jets obtained from different conical liners from a charge having 56mm-diameter is presented in this paper. An OFHC copper liner of thickness 1 mm and 54 mm-diameters is used for jet formation analysis. Charge ignition is made by using Point detonation method. The simulation results are obtained from Ansysis Autodyn 2-D hydrocode. Experiments are conducted for a charge having 600 conical liner. Flash X-ray Radiography is used for image capturing. The performance capacity of standard shaped charge is predicted by its penetration against steel target. It is observed that kinetic energy of the jet decreases as angle increases, also total energy of the explosive increases and hence the Ratio of the K.E of the jet to the total energy of the explosive decreases as the angle increases. Simulation results are compared with the experimental results. It is observed that simulation results are in favorable agreement within acceptable range of error with the experimental results.

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Naeem, K., A. Hussain, and A. Abbas. "A Review of Shaped Charge Variables for its Optimum Performance." Engineering, Technology & Applied Science Research 9, no. 6 (2019): 4917–24. https://doi.org/10.5281/zenodo.3566142.

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Shaped charge is a device for focusing the chemical energy of explosives to a particular point or line for penetration or cutting purpose respectively. They are used for the penetration or cutting of various types of targets on land, water, underground, underwater, or air. Their shape is either conical or linear and consists of explosive, casing and liner. The liner is bent towards the central axis producing a thin hypervelocity jet by the energy released as a result of the explosive detonation. This jet is utilized against the target. Shaped charges can perforate or penetrate targets like aircrafts, ships, submarines, armored vehicles, battle tanks, and bunkers. This paper presents a detailed review of analytical works, computer simulations, and experimental results related to the liner. Among modern diagnostic techniques flash x-rays, radiography is most used in the experiments performed in the last 40 years. Powder metallurgy, which started in the late twentieth century raised the efficiency of shaped charges to new altitudes. The efficiency of the shaped charge depends on numerous factors such as explosive’s type, liner’s material, geometry and metallurgy, manufacturing technique, and casing thickness. Factors concerning the liner’s material, metallurgical advancements, and geometry are discussed chronologically and in detail.

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Hebda, Kamil, Łukasz Habera, and Piotr Koślik. "Modelowanie numeryczne ładunków kumulacyjnych z wkładkami dzielonymi dwuczęściowymi." Nafta-Gaz 77, no. 4 (2021): 264–69. http://dx.doi.org/10.18668/ng.2021.04.06.

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The article was created on the grounds of numerical modelling of shaped charges with a focus on the unconventional shape of their liners. The standard shaped charge of the “deep penetrating” type is equipped with a conical liner made of copper. Three various geometries of shaped charges featuring unconventional shape have been modelled and compared with the classical model of a shaped charge. The shaped charges have been compared for maximum pressure during detonation, cumulative jet velocity, kinetic energy gained and length of cumulative jet after 22 µs. The purpose of modelling shaped charges, featuring unconventionally formed liners, was to check whether they are able to improve the perforation job parameters in oil and gas wells. Perforation of the borehole is a critical job, enabling the initiation of hydrocarbons production from a specific reservoir. The job consists in making series of channels perpendicular to the borehole axis, penetrating casing walls, the cement layer and the formation rock, in order to create a hydraulic link between the borehole and the reservoir of hydrocarbons. In the oil industry, the “deep penetrating” type shaped charges are designed in order to provide optimal length of the perforation channel, while maintaining its adequate perforating diameter. Nowadays, the most commonly deep-penetrating shaped charges used, are the axially-symmetric shaped charges with conical liners made of copper powders. The charges create a cumulative jet reaching a velocity of approx. 7000 m/sec and are able to penetrate up to 1 m of rock matrix in favourable conditions. The article describes the parameters of shaped charges, that have been obtained as a result of numerical modelling. In order to finally confirm the target penetrating ability by the modelled shaped charges, one should check their real physical models in fire-ground conditions.

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Jha, N. K., Deepankar Das, Ashutosh Tripathi, and R. N. Hota. "Acoustic damping: Analytical prediction with experimental validation of mixed porosity liners and analytical investigation of conical liners." Applied Acoustics 150 (July 2019): 179–89. http://dx.doi.org/10.1016/j.apacoust.2019.02.006.

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Schilling, Thomas J. "Reactive-Injecting Follow-Through Shaped Charges from Sequent-Material Conical Liners." Propellants, Explosives, Pyrotechnics 32, no. 4 (2007): 307–13. http://dx.doi.org/10.1002/prep.200700033.

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Khalid, Naeem, Hussain Arshad, and Abbas Shakeel. "A Review of Shaped Charge Variables for its Optimum Performance." Engineering, Technology & Applied Science Research 9, no. 6 (2019): 4917–24. https://doi.org/10.5281/zenodo.3559070.

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Svirsky, O. V., and M. A. Vlasova. "On the Penetration Capability of Shaped Charges with Conical and Hemispherical Liners." Combustion, Explosion, and Shock Waves 55, no. 6 (2019): 739–43. http://dx.doi.org/10.1134/s0010508219060169.

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Cui, Ping, Xinbao Gao, Jingqing Xu, et al. "Simulation and Experimental Study on Jet Velocity of Zr-Based Amorphous Alloy Liner." Metals 12, no. 6 (2022): 978. http://dx.doi.org/10.3390/met12060978.

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Zr-based amorphous alloy is a new energetic material that has been closely monitored and extensively studied for the design of highly effective shaped charge warheads in recent years. In order to accurately determine the motion parameters of shaped charge jets during the detonation-driven formation process of Zr-based amorphous alloy liners, we prepared conical ZrCuNiAlAg liners by vacuum die casting and supercooled liquid high-rheological-rate formation processes. Based on jet-formation numerical simulation, pulsed X-ray imaging and copper foil target velocity measuring tests were conducted to identify the variation trend of the jet velocity of Zr-based amorphous alloy liners with time. The jet velocities at typical moments in the free flight stage were verified. The research results showed that Zr-based amorphous alloy liners could produce solid jets, whose velocity was in gradient descent from the head to the tail, and that the jet’s head velocity peaked at 12 μs and then slowly decreased with time. The average velocities measured by the X-ray imaging and copper foil target tests were 6913 m/s and 7177 m/s, respectively, and both of them were in good agreement with the simulation results, verifying the accuracy of the numerical simulation model for jet formation. The formation processes of shaped charge liners were found to affect the mechanical properties of the material and thus, the jet’s formation process and motion parameters. The Zr-based amorphous alloy liner formed by the supercooled liquid-phase high-rheological-rate formation process exhibited a jet velocity 6.5% higher than that formed by the vacuum die casting process.

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Park, Leeju, Sanghyun Woo, Yerim Lee, Keunho Lee, and Young Sun Yi. "Comparison of dynamic tensile extrusion behaviour of WCu composites made by different processes." EPJ Web of Conferences 183 (2018): 03004. http://dx.doi.org/10.1051/epjconf/201818303004.

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Composites with 60~90% of tungsten are used in liners of some specialty shaped charges. The penetration is enhanced by a factor against copper for homogeneous steel target. Tungsten powder based shaped charge liners are also especially suitable for oil well completion. In this study, WCu composites manufactured by different process are used for testing of dynamic tensile extrusion (DTE) behaviour. One samples were made by copper infiltrated method. The other samples were manufactured by metal injection molding methods with reduced tungsten copper composite powder. DTE tests were carried out by launching the sphere samples (Dia. 7.62mm) to the conical extrusion die at a speed of ~375m/s. The DTE fragmentation behaviour of tungsten copper composites after soft-recovered were examined and compared with each other.

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Dou, Yipu, Zhengfeng Liang, and Jianhao Dou. "Numerical simulation study on the influence of the variation rate of the liner thickness on the damage performance of shaped charge." Journal of Physics: Conference Series 3021, no. 1 (2025): 012064. https://doi.org/10.1088/1742-6596/3021/1/012064.

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Abstract To investigate the impact of the variation rate of the thickness of the conical liner on the damage performance of shaped charge jet during its formation process, using the numerical simulation software Autodyn to construct a numerical model for conducting simulation computations. Subsequently, the corresponding numerical simulation results were acquired, and parameters such as velocity, mass, and penetration depth in the numerical simulation outcomes of shaped charge jet formed from liners with different thickness variation rates were analyzed. The findings reveal that the velocity at the head of jet ascends as the variation rate of the liner wall thickness increases. Meanwhile, jet head diameter diminishes with the augmentation of the thickness variation rate, and the penetration depth expands in tandem with the growth of the thickness variation rate.

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Hunger, Sandra, Alexander Seidler, Christian Rotsch, Christoph-Eckhard Heyde, and Welf-Guntram Drossel. "Evaluating the Feasibility and Reproducibility of a Novel Insertion Method for Modular Acetabular Ceramic Liners." Bioengineering 10, no. 10 (2023): 1180. http://dx.doi.org/10.3390/bioengineering10101180.

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Modern hip implants have a modular design. In case of wear or other damage it allows surgeons to change the tribological partners, i.e., the acetabular liner and femoral ball. In both revision and primary surgery, the secure joining of the implant components is important for the success of the operation. The two components, namely the ceramic liner and hip cup, are connected via a conical press connection and should be concentrically aligned to avoid chipping. Malseated liners can reduce the life span in situ. The amount of the joining force, which is usually applied via a hammer, depends on the surgeon. In this study, an alternative joining method for acetabular ceramic liners in hip cups was investigated, which intends to make the process more reproducible and thus safer. For this purpose, a handpiece was used to apply a defined force impulse of 4 kN. For the concentric alignment of a ceramic liner in the hip cup, an adapter was developed based on findings via a qualitative finite element (FE) analysis. Insertion and pushout tests of the acetabular cup–liner connection were performed in the laboratory with the new instrument (handpiece with the connected adapter) to evaluate the functionality of the instrument and the reproducibility of the new insertion method. For comparison, liners and acetabular cups were joined using a testing machine according to the standard. The presented results demonstrate the technical proof-of-concept of the new joining method under laboratory conditions. They meet the acceptance criteria of established manufacturers, which proves the equivalency to proven methods for joining modular implant components. To verify the improvement of the new joining method compared to the conventionally used joining method, an application-oriented study with different surgeons and the new joining instrument under clinical conditions is necessary.

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Puente Reyna, A. L., M. Holderied, M. Jäger, C. Schilling, and T. M. Grupp. "ARTICULATION AND BACKSIDE WEAR ANALYSIS AFTER LONG-TERM IN VITRO WEAR SIMULATION OF VITAMIN E STABILIZED POLYETHYLENE ACETABULAR LINERS WITH A PRESS-FIT LOCKING MECHANISM." Traumatology and Orthopedics of Russia 24, no. 2 (2018): 29–40. http://dx.doi.org/10.21823/2311-2905-2018-24-2-29-40.

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A previous retrieval study analyzed the backside wear of short-term implanted liners against in vitro tested liners of similar life in service and showed comparable results among both groups, with no significant backside wear due to micro-motion.The purpose — to obtain a picture of the overall wear (articulation and backside surfaces) of 0.1% vitamin e blended polyethylene liners, with a locking mechanism based on a press-fit cone in combination with a rough titanium conical inner surface in the fixation area, under a 20 million cycles hip wear simulation.Materials and Methods. A semi-quantitative method was used in order to assess the damage on the backside of the liners and a 3d measuring machine to assess the creep and wear at the articulation surface.Results. The total average backside wear score was 22.00±2.59 from a maximum total score of 147 after 5 million cycles (mc), increased to 31.92±5.57 after 10 mc, but showed no further increment after 15 and 20 mc. The reference liners (subjected only to axial load) showed similar wear scores and modes as the liners under wear simulation (axial load and movement). Small scratches produced during insertion and removal were clearly seen at the rim (fixation) area and no considerable abrasion was observed. The machining marks on the convex surface were always visible. Regarding the articulation surface, a steady state wear rate of 7 µm/year was measured.Conlusion. These results determined that most of the backside wear produced on the liners occurred during their insertion and removal rather than during their life in service. Moreover, the wear at the articulation surface was similar to that seen in vivo at short- and mid-term on highly cross-linked polyethylene liners with and without vitamin e content.

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Snowball, Ian, Bjarne Almqvist, Bryan C. Lougheed, Steffen Wiers, Stephen Obrochta, and Emilio Herrero-Bervera. "Coring induced sediment fabrics at IODP Expedition 347 Sites M0061 and M0062 identified by anisotropy of magnetic susceptibility (AMS): criteria for accepting palaeomagnetic data." Geophysical Journal International 217, no. 2 (2019): 1089–107. http://dx.doi.org/10.1093/gji/ggz075.

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SUMMARY Anisotropy of magnetic susceptibility data obtained from discrete subsamples recovered from two Integrated Ocean Drilling Program sites (Expedition 347 sites M0061 and M0062 in the Baltic Sea) by an Advanced Piston Corer are compared to results obtained on subsamples recovered by replicate 6-m-long Kullenberg piston cores. Characteristic natural remanence directions were obtained from the total of 1097 subsamples using principal component analyses. The three principal anisotropy axes of subsamples taken from Advanced Piston Core liners align to the subsample axes, with the maximum axis (K1) parallel to the split core surfaces, possibly caused by outwards relaxation of the core-liners after splitting. A second anomalous anisotropy fabric is characterized by steep values of the angular difference between the inclination of the minimum anisotropy axes (K3) and that expected for horizontal bedding (90°). This fabric is confined to the upper 1–2 m of the Kullenberg cores and specific sections of the advanced piston cores, and we attribute it to conical deformation caused by either excessive penetration speeds and downwards dragging of sediment along the edge of the liner or stretching caused by undersampling. By using our data in an example, we present a protocol to accept palaeomagnetic secular variation data that uses (i) a threshold 90-K3 value of 15°, combined with a modelled, locally applicable minimum inclination of 65° and (ii) an A95 cone of confidence based on Fisher statistics applied to virtual geomagnetic pole distributions.

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Pyo, Yeongmin, Taylor Robertson, Sean Yun, and Zekai Hong. "Experimental Evaluation of Using Silica Aerogels as the Thermal Insulator for Combustor Liners." Journal of the Global Power and Propulsion Society 4 (December 4, 2020): 202–16. http://dx.doi.org/10.33737/jgpps/129703.

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An experimental study was conducted for evaluating the feasibility of using silica aerogel as thermal insulator for combustor liners. Aerogels are a superior material for minimizing heat flux to the metal structure of the combustion liner due to their low thermal conductivity. In this study, a conical natural gas fired swirling-flame combustor was utilized for reproducing the combustion environment. The silica aerogel blanket was attached to the inner side of a perforated combustor liner. Temperature distribution on the outer side of the combustion liner was measured using a calibrated IR camera. To create a protective cooling film over the aerogel surface, cooling air was supplied from the back side of the perforated metal liner and was allowed to penetrate the silica aerogel blanket to be discharged to the combustor. As the combustor was operated at a fixed equivalence ratio of 0.83, cooling air flow rates were varied to evaluate the effectiveness of transpiration cooling on the aerogel blanket as various cooling flow rates. The measured evolution of temperature distribution confirmed thermal equilibriums for every test condition with transpiration cooling. The measured temperature distribution of metal liner demonstrated superior thermal insulation of aerogel blanket under the protection of cooling film with a temperature difference as high as 1580 K between combustion products temperature and the metal liner temperature on the back side. In addition, silica aerogel samples were examined before and after the combustion tests to understand their material degradation exposing to a typical gas turbine combustor environment using high-resolution scanning electron microscope (SEM). Test results suggest multiple degradation mechanisms to the silica aerogel blanket samples from the combustion tests. Improvements can be made to the silica aerogel blankets for a more resilient thermal insulator, for example, by replacing glass fibers in silica aerogels.

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Hussain, G., and K. Sanaullah. "COMPARATIVE PARAMETRIC NUMERICAL SIMULATIONS OF MATERIALS USED AS LINERS IN THE EXPLOSIVELY FORMED PROJECTILES (EFPs)." Nucleus 46, no. 3 (2020): 301–9. https://doi.org/10.71330/nucleus.46.03.960.

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A conventional shaped charge comprises a conical metal liner projecting a hyper velocity jet of metal that is able to penetrate to great depths into steel armour. However, misalignment problems exist in tandem with jet break up and spewing particles that greatly diminish its penetration power. An EFP, on the other hand, has a liner in the shape of a geometrical recess. The force of the blast molds the liner into a number of configurations, depending on the geometry and the explosive detonation characteristics. This paper presents comparative parametric numerical simulations of materials used as liners in the explosively formed projectiles EFPs. Numerical simulations are carried out using AUTODYN 2D hydrocode to study effects of linerâ€™s materials on the shape, velocity, traveled distance, time, pressure, internal energy, temperature, yield stress, divergence or stability, density, compression, and length to diameter (L/D) ratio of EFPs. These parameters are estimated at the instants of maximum as well as at stable velocities. The parametric study reveals that aluminum has maximum velocity in shortest time among the liner materials. From this reason, it was concluded effective standoff was greater for aluminum than more denser metals. Maximum velocity and traveled distance of Tantalum EFP is found to be minimum which may be due to low thermal softening exponent and larger hardening exponent. The simulated yield stress and pressure developed in the Fe EFP reaches at maximum. The L/D ratio for Copper is found to be maximum which supports maximum penetration. From the stability point of view, 1006 MS is found to be the most reliable liner material due to minimum divergence. Generally all liner materials have similar effects of all parameters like pressure, internal energy, temperature, yield stress, divergence or stability, density, compression at the instants of maximum as well as at stable velocities except L/D ratio of EFPs. At the instant of maximum velocity, L/D ratio of Ta and AL EFPs have minimum and maximum L/D ratio respectively whereas Fe and Cu EFPs have minimum and maximum L/D ratio respectively. The velocity attenuation laws for liner materials from maximum to stable velocities are determined and plotted. The EFPs observed at maximum velocities are profilic except tantalum which shows a straight profile one due to higher density. The velocity attenuation laws show material for which maximum and stabilized velocity come earlier than other materials whereas tantalum is the linerâ€™s material for which maximum and stabilized velocity take more time than other materials due to lower and higher densities respectively.

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Peng, Chucai, Chufan Ding, Bin Chen, et al. "Air-Backed Aluminum Shells Subjected to Underwater Penetration: Torpedo Interception Simulations." Journal of Marine Science and Engineering 11, no. 2 (2023): 392. http://dx.doi.org/10.3390/jmse11020392.

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Underwater torpedoes have become a serious threat to ocean liners and warships, and the interception against attacking torpedoes is always the hotspot in marine engineering. To simulate the underwater torpedo interception by a high velocity projectile, this work numerically deals with the process of projectile water entry and sequent penetration into underwater aluminum shells, whereby conical and ogival nose projectiles are comparatively studied. With the arbitrary Lagrange–Euler (ALE) algorithm adopted to describe fluid medium, the projectile water entry model is developed and validated against the test data. Similarly, the penetration model validation is made by modeling a tungsten ball perforation on an aluminum plate. Covered by water fluid, the air-backed aluminum shell is utilized to simulate an underwater torpedo subjected to projectile impact. The numerical predictions of underwater penetration reveal that ogival nose projectiles have a superior performance in underwater motion and perforation while conical nose counterparts deteriorate the shell targets more severely. For 20 cm, 40 cm and 60 cm underwater depth scenarios, a numerical prediction suggests that the energy consumed by water is proportional to the water depth, meanwhile aluminum shell perforation absorbs almost the identical projectile kinetic energy. Such findings may shed some light on the nose shape optimization design of high velocity projectile intercepting underwater torpedoes.

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Kottner, Radek, Richard Hynek, Tomáš Mandys, and Jan Bartošek. "Material property determination of the lining layers of a versatile helmet." MATEC Web of Conferences 157 (2018): 06005. http://dx.doi.org/10.1051/matecconf/201815706005.

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This paper deals with material property identification of a helmet lining consisting of an outer layer of an expanded polystyrene (EPS) and inner layer of an open-closed cell foam (OCCF). A combined numerical simulation and experimental testing was used for the material property identification. Compression and drop tests were performed. The ABAQUS finite element commercial code was used for numerical simulations in which the OOCF was modelled as a rate dependent viscoelastic material, while the EPS as a crushable foam. The reaction force time histories coming from the numerical simulation and the experiment have been used as a criterion for material parameter determination. After the identification of the material properties, numerical drop-tests were used to study the behaviour of a plate and a conical composite OOCF and EPS liners to decide which of them suits more for the helmet.

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Ladov, S. V., Ya M. Nikol’skaya, and S. V. Fedorov. "Numerical Analysis of the Formation of Shaped-Charge Jets from Charges with Conical and Semi-Spherical Liners of Variable Thickness." Combustion, Explosion, and Shock Waves 55, no. 4 (2019): 466–70. http://dx.doi.org/10.1134/s0010508219040130.

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Meng, Qingxiang, Yaping Zhao, and Zaiyou Yang. "Meshing limit line of the conical surface enveloping conical worm pair." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 2 (2019): 693–703. http://dx.doi.org/10.1177/0954406219878755.

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In this study, the calculating principle of the meshing limit line of the conical surface enveloping conical worm pair is put forward systematically. The tooth face equations, the meshing function and the meshing limit function of a conical worm pair are all acquired. Investigating the meshing limit line is come down to solving an equivalent unary nonlinear equation, which is determined from its original equations with four variables by means of the elimination technique. Based on this, the meshing limit line characteristics are deeply researched after resolving preceding equation correctly. The numerical results declare that there may be two meshing limit lines on each helicoid of one tooth of an enveloping conical worm although not all of them have physical significance. All the significative meshing limit lines usually do not get into the worm helicoid and have no influence on its normal work. Therefore, the active length of the worm depends on the tooth face boundary of the conical worm wheel theoretically. Besides, when the center distance of the worm pair is less, the transmission ratio is larger and the number of thread of the worm is more, the meshing limit line may be closer to the little end of the conical worm e helicoid.

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Wang, Yifan, Zhijun Wang, Yongjie Xu, and Zhen Jin. "The Effect of Cylindrical Liner Material on the Jet Formation and Penetration Capability of Cylinder-Cone-Shaped Charge." Materials 15, no. 10 (2022): 3511. http://dx.doi.org/10.3390/ma15103511.

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The jet formation and penetration capacity of cylinder-cone-shaped charges against steel targets were studied using the method of numerical simulation. Cylinder-cone-shaped charge models with five cylindrical liner materials, including nickel, tungsten, tantalum, steel 4340 and copper, were established to investigate the penetration capability and were compared with the classical conical-shaped charge. Moreover, the influence of the connection method of the cylindrical liner and the truncated liner on the jet performance was examined. The results show that the head velocity of the projectile formed by the cylinder-cone-shaped charge with a cylindrical nickel liner was larger than that with other cylindrical liner materials; in addition, it was larger by 50.2% compared with that formed by the classical conical-shaped charge. The penetration depth of the steel target by the cylinder-cone-shaped charge with a cylindrical copper liner was the largest, which could be 51.7% higher than that of a classical conical-shaped charge at a standoff of 2.5 D. For 2.0 D and 2.5 D standoff distances, the penetration depths were increased by 18.4% and 29.5%, respectively, by using the connection method of putting the cylindrical nickel liner on the neck of the truncated liner compared with that of the previous cylinder-cone-shaped charge with a cylindrical nickel liner.

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Belyakov, V. A. "Kossel Lines and X-ray Localized Conical Modes." Journal of Experimental and Theoretical Physics 132, no. 3 (2021): 323–33. http://dx.doi.org/10.1134/s1063776121030122.

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Belyakov, Vladimir Alekseevich. "Kossel lines and X-ray localized conical modes." Acta Crystallographica Section A Foundations and Advances 77, a2 (2021): C308. http://dx.doi.org/10.1107/s0108767321093752.

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Денисова, Е., E. Denisova, Тимур Хуснетдинов, Timur Husnetdinov, Марианна Воронина, and Marianna Voronina. "Projection by Conical Helical Lines With Constant Pitch." Geometry & Graphics 6, no. 3 (2018): 13–19. http://dx.doi.org/10.12737/article_5bc4563ccf6884.11983902.

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This paper’s purpose is investigation of non-traditional projection systems and their projecting surfaces, the choice of such congruence parameters for conical helical lines, which allow cover the whole complex of requirements to the surface, obtained by projecting of an arbitrary flat or spatial line with congruence beams, as well as the use of computer graphics in surface visualization. In the paper has been presented an example of analytical interpretation for an image of curvilinear projection by conical helical lines with constant pitch, and a congruence example for conical helical lines located on coaxial cones with a common vertex and a variable angle of generatrix inclination to an axis. Have been investigated properties and defined parameters of the congruence helical line passing through a space arbitrary point which is not belonging to an axis. An approach for construction of spiral surfaces, which frame consists of beams projecting an arbitrary line. A form generation of surfaces by analytical methods and their visualization by means of computer graphics is one of applied geometry’s urgent problems in connection with the use of such methods in automated systems for scientific research, design, and manufacture on equipment with computer numerical control. The leading research method for this problem is the general analytical theory for surfaces’ applied form generation developed by Professor I.A. Skidan and formed a unique apparatus, based on mathematical support of computing technologies for design and creation of objects with complex forms. On examples of visualization for projecting surfaces by means of computer graphics it is possible to show applicability of analytical models in computer technologies for scientific researches, design and manufacturing.

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Denisova, E. V., M. V. Voronina, and Z. O. Tretyakova. "Projecting by conical screw lines with constant step." IOP Conference Series: Materials Science and Engineering 451 (December 14, 2018): 012120. http://dx.doi.org/10.1088/1757-899x/451/1/012120.

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Denisova, E. V., M. V. Voronina, and Z. O. Tretyakova. "Projecting by conical screw lines with constant step." IOP Conference Series: Materials Science and Engineering 451 (December 14, 2018): 012120. http://dx.doi.org/10.1088/1742-6596/451/1/012120.

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Taras, І. P., and T. O. Pryhorovska. "Study on geometric features of conical threads." Scientific Bulletin of Ivano-Frankivsk National Technical University of Oil and Gas, no. 1(48) (June 29, 2020): 16–22. http://dx.doi.org/10.31471/1993-9965-2020-1(48)-16-22.

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The article studies the problem of oil/gas pipe conical thread reinforcement; in particular, the geometrical fundamentals for tool design for reinforcement. The article considers the main types of conical threads for pipes used in oil/gas industry. It was determined, that to obtain initial data for tools, used to reinforce thread crest and flank, it is necessary to consider conical threads not only as helical lines, but also as helicoid surfaces, to determine what helicoid parameters make the thread conical and obtain relations for the calculation of these geometric parameters. The authors determined geometrical parameters of conical threads and design parameters to develop rollers with deformed protrusions for simultaneous reinforcement of aforementioned thread crests and flank to improve tools for their frictional reinforcement. It was stated, that contrary to cylindrical threads, helicoid’s angles of inclination, which form conical threads, differ not only by the angle of inclination to the plane normal to their axes, but also by the values. The study of conical thread geometrical features refers to a cylindrical one allows to use these features in the design or improvement of tools for its manufacture and/or reinforcement. This approach allows improving the tools for frictional reinforcement of conical locking threads by modifying the lateral deforming elements. It makes possible to simplify tool manufacture, increase tool durability, reinforce the conical thread surface, and improve the quality, performance and economy of the conical thread frictional reinforcement.

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Naeem, K., A. Hussain, and S. Abbas. "A Review of Shaped Charge Variables for its Optimum Performance." Engineering, Technology & Applied Science Research 9, no. 6 (2019): 4917–24. http://dx.doi.org/10.48084/etasr.3153.

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Shaped charge is a device for focusing the chemical energy of explosives to a particular point or line for penetration or cutting purpose respectively. They are used for the penetration or cutting of various types of targets on land, water, underground, underwater, or air. Their shape is either conical or linear and consists of explosive, casing and liner. The liner is bent towards the central axis producing a thin hypervelocity jet by the energy released as a result of the explosive detonation. This jet is utilized against the target. Shaped charges can perforate or penetrate targets like aircrafts, ships, submarines, armored vehicles, battle tanks, and bunkers. This paper presents a detailed review of analytical works, computer simulations, and experimental results related to the liner. Among modern diagnostic techniques flash x-rays, radiography is most used in the experiments performed in the last 40 years. Powder metallurgy, which started in the late twentieth century raised the efficiency of shaped charges to new altitudes. The efficiency of the shaped charge depends on numerous factors such as explosive’s type, liner’s material, geometry and metallurgy, manufacturing technique, and casing thickness. Factors concerning the liner’s material, metallurgical advancements, and geometry are discussed chronologically and in detail.

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Carlotto, Alessandro, and Camillo De Lellis. "Min-max embedded geodesic lines in asymptotically conical surfaces." Journal of Differential Geometry 112, no. 3 (2019): 411–45. http://dx.doi.org/10.4310/jdg/1563242470.

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31

Wang, Y. W., H. Y. Liang, and S. Y. Wang. "Collapse deformation simulation of metal liner under coupling of multi-physics field." Journal of Physics: Conference Series 2478, no. 2 (2023): 022015. http://dx.doi.org/10.1088/1742-6596/2478/2/022015.

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Abstract In order to study the collapse deformation mechanism of metal liner under coupling of multi-physics field, the input current was obtained through circuit design and simulation by Multisim. The results show that the peak input current is determined by the capacitor voltage. The coupling simulation of electromagnetic-thermal-mechanical field was carried out by using LS-DYNA software. The influence mechanism of liner on the collapse deformation of the metal liner is analysed. The collapse deformation of liner with cylindrical tip is different from that of traditional liner. The tip of the cylinder is beneficial to utilizing the high pressure in the centre of the cylinder. But the micro-element at the top of the cone collapse to the axis with decreasing velocity along the outer contour of the tip. For the conical metal liner with cylindrical end, the current peak needs to reach more than 2 MA to make the liner obtain sufficient collapse velocity. The collapse velocity of conical metal liner element increases with the decrease of wall thickness, while the collapse velocity of bottom liner element decreases with the increase of cone diameter and cone height.

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Javier, Cebeiro, Nguyen Mai K., Rollet Genevi`eve, and Dumas Laurent. "AN ANALYTIC INVERSION FORMULA FOR A RADON TRANSFORM ON A CLASS OF CONES." Eurasian Journal of Mathematical and Computer Applications 10, no. 3 (2022): 73–83. http://dx.doi.org/10.32523/2306-6172-2022-10-3-73-83.

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Since the works of Radon and Cormack on the classical Radon transform on straight lines, several generalizations involving integrations on conical surfaces have been studied. In this article, we introduce a new family of conical surfaces with arbitrary vertices of the space and axes through the origin and study the corresponding Radon transform. We derive its analytical inversion in two and three dimensions. Numerical simulations are carried out for the two-dimensional case.

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33

Purata Sifuentes, Omar Jair. "Indirect Determination of the Internal Diameter of Glass Conical Volumetric Instruments." Entreciencias: Diálogos en la Sociedad del Conocimiento 11, no. 25 (2023): 1–13. http://dx.doi.org/10.22201/enesl.20078064e.2023.25.85557.

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Purpose: To determine the values of the internal diameter in conical-shaped glass volumetric instruments using height measurements, without needing to measure the wall thickness of the volumetric container, which will allow calculating the contribution to the uncertainty of volume measurement due to the adjustment of the meniscus. Methodological design: The proposed method approximates volume by a series of truncated cones bounded by instrument graduation lines. The series of truncated cones thus defined is subject to comply with a geometric restriction. Then, for the graduation lines of the volumetric instrument that did not adhere to the constraint, a power regression model allows approximation of the value of the internal diameter. Results: The proposed approach could be used as an alternative method to determine the internal diameter of glass conical volumetric instruments in cases where using a vernier caliper or optical comparator is not an option, either because the geometry of the conical instrument does not allow it or because higher cost instruments are not available. Research limitations: Only two types of conical volumetric instruments were tested: an Imhoff cone and a centrifuge tube, with scopes of 1 L and 100 mL, respectively, from only two commercial brands of laboratory glassware. The volume of the tip of the instrument was modeled up to the first graduation mark, always as a semi-ellipsoid of revolution. Findings: Comparing the direct measurement of the internal diameter of the volumetric instruments with an optical comparator, there is an average relative error below 10 %, with a maximum value below 20 % for the two different conical glass instruments studied.

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M. Dezhkam, M. Dezhkam, and A. Zakery A. Zakery. "Exact investigation of the electronic structure and the linear and nonlinear optical properties of conical quantum dots." Chinese Optics Letters 10, no. 12 (2012): 121901–4. http://dx.doi.org/10.3788/col201210.121901.

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35

Marinov, Marin, and Petya Asenova. "Teaching the Notion Conic Section with Computer." Mathematics and Informatics LXIV, no. 4 (2021): 395–409. http://dx.doi.org/10.53656/math2021-4-5-pred.

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The article discusses the problem of introducing and constructing mathematical concepts using a computer. The Wolfram Mathematica 12 symbolic calculation system is used at each stage of the complex spiral process to form the notion of conic section and the related concepts of focus, directrix and eccentricity. The nature of these notions implies the use of appropriate animations, 3D graphics and symbolic calculations. Our vision of the process of formation of mathematical concepts is presented. The notions ellipse, parabola and hyperbola are defined as the intersection of a conical surface with a plane not containing the vertex of the conical surface. The conical section is represented as a geometric location of points on the plane for which the ratio of the distance to the focus to the distance to the directrix is a constant value. The lines of hyperbola and ellipse are determined by their foci. The equivalence of different definitions for conical sections is commented.

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36

Ikuta, Kazunari, and Magne Kristiansen. "Conical Liner Implosion as a Projectile Injector for Mass Drivers." Japanese Journal of Applied Physics 25, Part 2, No. 3 (1986): L198—L199. http://dx.doi.org/10.1143/jjap.25.l198.

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37

Pai, V. V., V. M. Titov, Ya L. Luk’yanov, and A. V. Plastinin. "Instability of a Conical Liner during Shaped-Charge Jet Formation." Combustion, Explosion, and Shock Waves 55, no. 4 (2019): 434–38. http://dx.doi.org/10.1134/s0010508219040099.

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38

Braasch, Jonas. "Sounding saxophones like flutes." Journal of the Acoustical Society of America 155, no. 3_Supplement (2024): A151. http://dx.doi.org/10.1121/10.0027130.

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The saxophone can be modified with alternative non-single-reed tone generators, including double and free reeds and brass-instrument mouthpieces. It can also be played as a rim flute on the neck, which is a known extended technique for the saxophone. Flutes differ fundamentally from the other tone-generator types as they do not act like a valve, and their flutes are so-called open-open resonator instruments, while reeds and the lips in brass instruments effectively close one end of the resonator. As a practical consequence, all open-close hole key combinations result in fundamentally different pitches known from the regular saxophone. The fact that the saxophone is conically shaped, while the flute is typically cylindrical or inverse conical, further complicates the matter. Approaches to playing the saxophone as flute using alternative fingering combinations will be discussed along with measures of pitch accuracy, timbral, and level balance. While the achievable range aligns with many orchestral wind instruments, complex cross-fingerings make it difficult to play fast chromatic lines. The large bore of the saxophone gives the flute sound a dark character, more like a Native American flute or shakuhachi than a Western concert flute or recorder.

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39

Choi. "Performance estimation of conical picks with slim design by the linear cutting test (I): depending on attack angle variation." Journal of Korean Tunnelling and Underground Space Association 16, no. 6 (2014): 573. http://dx.doi.org/10.9711/ktaj.2014.16.6.573.

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40

Choi. "Performance estimation of conical picks with slim design by the linear cutting test (II): depending on skew angle variation." Journal of Korean Tunnelling and Underground Space Association 16, no. 6 (2014): 585. http://dx.doi.org/10.9711/ktaj.2014.16.6.585.

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Кокарева, Я., and Ya Kokareva. "Synthesis of Equations For Ruled Surfaces With Two Curvilinear And One Rectangular Directrixes." Geometry & Graphics 6, no. 3 (2018): 3–12. http://dx.doi.org/10.12737/article_5bc454948a7d90.80979486.

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Ruled surfaces have long been known and are widely used in construction, architecture, design and engineering. And if from the technical point of view the developable surfaces are more attractive, then architecture and design successfully experiment with non-developable ones. In this paper are considered non-developable ruled surfaces with three generators, two of which are curvilinear ones. According to classification, such surfaces are called twice oblique cylindroids. In this paper has been proposed an approach for obtaining of twice oblique cylindroids by immersing a curve in a line congruence of hyperbolic type. Real directrixes of such congruence are a straight line and a curve. It has been proposed to use helical lines (cylindrical and conical ones) as a curvilinear directrix, and a helical line’s axis as the straight one. Then the congruence’s rectilinear ray will simultaneously intersect the helical line and its axis. Congruence parameters are the line’s pitch and the guide cylinder or cone’s radius. The choice of the curvilinear directrix is justified by the fact that the helical lines have found a wide application in engineering and architecture. Accordingly, the helical lines based surfaces can have a great potential. In this paper have been presented parametric equations of the considered congruences. The congruence equations have been considered from the point of view related to introducing a new curvilinear coordinate system. The obtained system’s coordinate surfaces and coordinate lines have been also studied in the paper. To extract the surface, it is necessary to immerse the curve in the congruence. To synthesize the equations has been used a constructive-parametric method based on the substitution of the immersed line’s parametric equations in the congruence equations according to a special algorithm. In the paper have been presented 5 examples for the synthesis of ruled surfaces equations such as the twice oblique cylindroid and their visualization. The method is universal and algorithmic, and therefore easily adaptable for the automated construction of surfaces with variable parameters of both the congruence and the immersed line.

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Dashtian Gerami, Nasser, Gholam Hossein Liaghat, Gholam Hossein Rahimi, and Najmeh Khazraiyan. "The effect of concrete damage on the penetration depth by the tandem projectiles." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 6 (2017): 1020–32. http://dx.doi.org/10.1177/0954406217700178.

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Tandem projectile is one approach of the development of anti-structure concrete projectile, which is made of the forward shape charge and the follow-through projectile. In this paper, in order to study the performance of anti-structure tandem projectiles, experimental and numerical analyses of the penetration process were performed for forward shape charge with conical copper liner hitting into the concrete targets. Having a well agreement, numerical and empirical results indicate that a forward shape charge with a conical copper liner will make appropriate tunnel diameter through the concrete targets. Following the validation of the applied numerical method, numerical simulations were conducted for the penetration of the follow-through projectile, by three different concrete targets: undamaged concrete, pre-drilled concrete, and damaged pre-drilled concrete. The parametric results show that the damaged pre-drilled concrete affects the penetration depth and residual velocity of the follow-through projectile significantly.

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43

Pai, V. V., V. M. Titov, Ya L. Luk’yanov, and K. M. Zubashevskii. "Temperature Measurement of the Shaped-Charge Jet from a Conical Liner." Combustion, Explosion, and Shock Waves 56, no. 3 (2020): 361–64. http://dx.doi.org/10.1134/s0010508220030132.

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44

NOJIMA, Taketoshi, and Takeyuki KAMEI. "Origami-Modellings of Foldable Conical Shells Consisting of Spiral Fold Lines." Transactions of the Japan Society of Mechanical Engineers Series C 68, no. 667 (2002): 1009–14. http://dx.doi.org/10.1299/kikaic.68.1009.

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Kudyakov, Konstantin, and Andrey Buchkin. "Centrifugal concrete poles for transmission lines reinforced with prestressed FRP rebar." E3S Web of Conferences 410 (2023): 02011. http://dx.doi.org/10.1051/e3sconf/202341002011.

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Reinforced with steel rebar concrete centrifuged conical poles for power transmission poles receive corrosion damage to steel reinforcement during operation. These damages can lead to the failure of structures. Complete replacement of both longitudinal and transverse steel reinforcement by composite one is a way to increase the reliability and durability of such structures. This method also allows the use of cost-effective concretes with a low cement content. The research results have shown the viability of such solutions, but the use of composite reinforcement requires its prestressing. This article discusses the Russian practice of testing concrete centrifuged conical poles for strength, crack resistance and rigidity. A brief description of the prototypes and methods of their testing is given. The main results of bending tests of full-scale test samples are presented in the form of diagrams of their deformation. Analysis of the results showed that the test samples of poles are correspond to requirements of Russian norms for deformability, crack resistance and strength. According to the results the studied centrifugal concrete poles with prestressed longitudinal GFRP rebars and transverse spiral GFRP rebars are like traditional ones with steel reinforcement (in standardized strength, crack resistance and deflection values) and, therefore, can be used in building construction.

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46

Maleki, S., and M. Tahani. "An investigation into the static response of fiber-reinforced open conical shell panels considering various types of orthotropy." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 1 (2013): 3–21. http://dx.doi.org/10.1177/0954406213480585.

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In this study, bending of composite open conical shell panels subjected to various distributed mechanical loads with various types of orthotropy is investigated. The stiffness coefficients are assumed to be functions of the meridional and circumferential coordinates in panels, which are produced by various methods for the realistic applications. In the first case of orthotropic open conical shell panels, the orientation of fibers are assumed to be in the meridional and circumferential directions. The stiffness coefficients of this type of fiber-reinforced panel are usually assumed to be constant. It is shown that due to the geometry of the conical surface, thickness of laminate will be changed along the meridional direction. The effect of stiffness variation on the response of panel is considered for the first time. In the case of open conical shell panel, which is fabricated by molding the prepreg layers around a conical-shaped mandrel, angle between fibers and meridional lines and, consequently, stiffness coefficients are assumed to be functions of the circumferential coordinates. In the third type, open conical shell panel can be made by cutting from a filament wound circular conical shell. In this case, thickness and ply orientation are functions of the shell coordinates. In this article, different path definitions for variable stiffness filament wound shells are considered. The inclusion of this geometric complicating effect in static analysis will add considerably to the complication and cost of a solution scheme. This article presents some results to show when these assumptions have a significant effect on the end result. The governing equations are based on the first-order shear deformation theory. The governing equations are discretized at whole domain grid points, and the boundary conditions are implemented exactly at boundary grid points using the generalized differential quadrature method. Application of the generalized differential quadrature to the governing equations, solution domain and boundary conditions leads to a system of algebraic equations. Various combinations of clamped, simply supported and free boundary conditions are implemented. It is found that the present method can accurately analyze fiber-reinforced open conical shell panels with various types of orthotropy.

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P, Aravind, and M.Girirajkumar S. "Performance Optimization of PI Controller in Non Linear Process using Genetic Algorithm." Performance Optimization of PI Controller in Non Linear Process using Genetic Algorithm 3, no. 5 (2013): 1968–72. https://doi.org/10.5281/zenodo.5517052.

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Recently, through the use of soft computing techniques fine tuning of PID controller parameters are carried out for non linear process. In this paper the Genetic Algorithm (GA) optimization technique, is successfully applied for tuning PI controller used in conical tank level process and hence to minimize the integral time absolute error (ITAE). A conical tank level process is represented as first order plus dead time transfer function. It is obtained by deriving mathematical differential equation and implemented in MATLAB. The main objective is to obtain a minimum rise time, minimum setting time, stable and controlled system by tuning the PI controller using Genetic Algorithm optimization technique. The incurred value is compared with the adaptive tuning techniques like gain scheduling and is proved better. The obtained simulation results demonstrate that this GA-based PI tuning approach is really a potential method gives minimum rise time (Tr), minimum settling time (Ts) and reduces the ITAE

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48

Liu, Jen-Yu, and Hong-Sen Yan. "Surface Geometry of Variable Pitch Cylindrical Cams with Conical Meshing Elements." Journal of Mechanical Design 116, no. 3 (1994): 862–66. http://dx.doi.org/10.1115/1.2919461.

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This paper presents mathematical expressions for the surface geometry of variable pitch cylindrical cams with four conical meshing elements based on the theory of conjugate surfaces. The unit normal of the element is derived, with given surface geometry of the meshing element, by differential geometry. The contact lines of the conjugate surface are defined according to the equation of meshing and the specified input-output relation. By the coordinate transformation of contact lines, we have the complete profile of the variable pitch cylindrical cam. The results of this work are instrumental in computer-aided manufacturing of variable pitch cylindrical cams for industrial applications.

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Múnera, Gladis E., Wim Bert, and Wilfrida Decraemer. "Morphological and molecular characterisation of Pratylenchus araucensis n. sp. (Pratylenchidae), a root-lesion nematode associated with Musa plants in Colombia." Nematology 11, no. 6 (2009): 799–813. http://dx.doi.org/10.1163/156854109x415524.

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Abstract Pratylenchus araucensis n. sp., a root-lesion nematode from Musa plants in Colombia, is described and illustrated. The new species is characterised by a combination of the following features: female small to medium sized (376-511 μm) with slender body, lip region with two lip annuli, sometimes an incomplete third annulus, face view characterised by complete fusion of the lip sectors to each other and to oral disc, resulting in a plain and smooth face, anterior surface of the oral disc may be low-conical or flat with rounded edges, short and robust stylet (mean 15.3 μm), short pharyngeal glands (mean 24.2 μm), lateral field with four parallel, non-equidistant lines and middle ridge narrower than outer ones, outer lines with partial areolation and lines converging posterior to the phasmid which is located at mid-tail, vulva located at 78% of total body length and lips well developed, often protruding, posterior uterine sac short (mean 18.1 μm), oval to slightly round spermatheca filled with round sperm, tail clearly conoid in half of population but subcylindrical (25%) or continuous grading from conical to subcylindrical in rest of population, tail terminus variable in shape, mostly conical rounded or rounded; males abundant, spicule 19 μm long. The sequence comparison of the D2D3 rDNA expansion region clearly separates in different clades the new species from P. jaehni, P. loosi and P. coffeae, the only three described species of Pratylenchus that also reproduce by amphimixis and which have lip regions with two lip annuli and a smooth face. Clear autapomorphic characters were present in the D2D3 expansion region of 28S rDNA in all specimens analysed and for both clades of P. araucensis n. sp. and its sister species P. jaehni.

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Butrym, Alexander Yu, and B. A. Kochetov. "MODE EXPANSION IN TIME DOMAIN FOR CONICAL LINES WITH ANGULAR MEDIUM INHOMOGENEITY." Progress In Electromagnetics Research B 19 (2010): 151–76. http://dx.doi.org/10.2528/pierb09102606.

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Journal articles on the topic 'Conical liners'

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