Cylindrical Diameter Research Articles

Design and Modeling of a Magnetic-Coupling Monostable Piezoelectric Energy Harvester Under Vortex-Induced Vibration

Vortex-induced vibration (VIV) is used by piezoelectric energy harvesters to generate electricity from wind and water flow. In this study, we introduce the nonlinear magnetic force into piezoelectric energy harvesters and develop a nonlinear monostable piezoelectric VIV transducer. We build a distributed-parameter model based on the Euler-Bernoulli beam theory and Kirchhof's law to analyze the dynamic responses of the magnetic-coupling piezoelectric energy harvester (MCPEH). Model results show that the performance of the MCPEH varies greatly with the increase of the load resistance and the length of the used PZT. There are two optimal resistance values for the MCPEH. When $R<; 31.6~\text{k}\Omega $ , both the external load resistance and the PZT length affect the maximum power output. The little optimum resistance value will dwindle with the increase of the PZT length, whereas the large optimum resistance value still fixes at 1.78 $\text{M}\Omega $ with the increase of the PZT length. Due to the resistive shunt damping effect and the kinetic energy of wind, the resonance domain becomes wider in these ranges of load resistance smaller than 31.6 $\text{k}\Omega $ and larger than 316 $\text{k}\Omega $ comparing that when the load resistance is larger than 31.6 $\text{k}\Omega $ and smaller than 316 $\text{k}\Omega $ . Besides, the performance is enhanced by the monostable nonlinear magnetic force, which can be improved by decreasing the value of the distance between moving magnets and fixed magnets. The energy harvester shows a maximum power output of 0.21 mW under excitation of wind velocity is 1.6 m/s when the cylindrical diameter is 20 mm, the PZT length is 30 mm and the load resistance is 0.5 $\text{M}\Omega $ .

Novel design and diagnostics improvements for increased production capacity and improved reliability at the Los Alamos Isotope Production Facility

The Isotope Production Facility (IPF) at Los Alamos National Laboratory (LANL) is used to produce an array of isotopes for medical, global security, and research applications with an intense beam of protons supplied by the linear accelerator at the Los Alamos Neutron Science Center (LANSCE). An Accelerator Improvement Project (AIP) was recently conducted at IPF to improve facility reliability and reduce programmatic risk while increasing general isotope production capacity and flexibility. This was accomplished through the installation of an improved beam window assembly, more robust beam diagnostics, an active and adjustable collimator, and a new beam rastering system. This paper will highlight the four exciting innovations and how they were designed, validated, and installed in parallel as well as the significant operational advantages they provide to IPF. Key experiments and the increased currents achieved in routine production runs demonstrating the enhanced capability from the AIP will be presented. The most notable capability enhancements include irradiations with beam currents ranging from 100 nA experimental runs up to 300 μA on routine production targets and utilization of a range of cylindrical target diameters.

Pier scouring reduction using a Strip Guide Flow Panel device

A set of laboratory experiments were conducted to study the effect of using a Strip Guide Flow Panel device to reduce scour process effects around a bridge pier. Three cylindrical piers of different diameter values and three different Strip Guide Flow Panel devices were used. Every Strip Guide Flow Panel device is simulated by two arms connected together at one of their edges at a right angle. The length of every arm is selected in a way to cover the pier diameter. Every Strip Guide Flow Panel was mounted on the upstream face of the corresponding cylindrical pier diameter at elevation adjacent to the flume bed. A uniform sized sediment were used as a bed material. Based on the experimental data, an acceptable range of scour reduction efficiency (35.71-66.67%) and high hydraulic safety factors were obtained when using Strip Guide Flow Panel. Also it is found that the scour depth when using Strip Guide Flow Panel is small comparing with corresponding potential and maximum scour depth values. So it can be concluded that the Strip Guide Flow Panel device can work like a turbulence kinetic energy dissipater to reduce the risk of scour around the pier during the serviceability life of bridge structure.

Experimental study of mini-hydrocyclones with different vortex finder depths using Particle Imaging Velocimetry

Characterization of flow field inside the hydrocyclone is helpful in optimizing hydrocyclone structure design. In this work, flow patterns in a mini-hydrocyclone with various vortex finder depths were studied with Particle Image Velocimetry (PIV). Axial velocity and radial velocity distributions of the central plane orthogonal to the inlet of mini-hydrocyclone were acquired, streamline diagrams were constructed from the measured vectors, and calculated from the experimental data. An analysis of the experimental data shows that the structural parameters of hydrocyclones have a critical impact on the flow field structure, and the experiment operation conditions only have an influence on strength of the flow fields. Vortex finder depth has a significant influence on the volume of the main separation zone and separation performance of mini-hydrocyclone. The optimal depth of the vortex finder was found to be a ratio of vortex finder depth to mini-hydrocyclone cylindrical section diameter L0/D of 1.0.

Film Cooling Performance for Cylindrical Holes Embedded in Contoured Craters: Effect of the Crater Depth

The present study deals with the flow field and cooling performance for flat-plate cylindrical film cooling holes embedded in contoured craters, especially considering the effect of the crater depth. A. test matrix of the crater depth ranging from 0.25 to 1.25 times of the cylindrical hole diameter and the blowing ratio ranging from 0.5 to 2.0 is used in CFD computations. The numerical results show that the flow fields downstream from the hole exit can be altered significantly due to interaction between the ejected coolant and contoured crater. The cooling performance depends on both the specific crater depth and blowing ratio; however, the cratered hole is always superior to the cylindrical hole in terms of the area-averaged cooling effectiveness regardless of the crater depth and blowing ratio. The cratered hole with a. crater depth equal to the hole diameter is recommended.

Determination of the stress state in the deformation zone under local loading

Based on the theory of small elastoplastic deformations and the finite element method, a mathematical model of local loading was created using the ANSYS application program, which allows determination of the stress state in the deformation zone and residual stresses in the hardened part. Paper studies the influence of various factors on the stress state: ball diameter, penetration depth and the cylindrical sample diameter. The results show that using the finite element method in the analysis of technological processes of hardening gives a deeper understanding of the stress development that occurs during the deformation of the workpiece. The process in question can be implemented without the use of environmentally hazardous lubricating cooling technological means, which makes it possible to attribute it in the future to one of the types of green mechanical processing technologies.

Groundwater Conservation with Hole Infiltration of Biopore Cube

Analysis of groundwater conservation with cube biopore infiltration holes using the value of soil permeability, the amount of rainfall, and the depth of the groundwater level. The groundwater conservation research method is carried out by making the cavity biopore infiltration holes to absorb the volume of rainwater and domestic waste water into the soil. Conservation is suitable for homes that have enough yard. The main reason is to use cube infiltration holes to accommodate large and small organic waste. Organic waste is trees, grass and domestic waste. For a small house yard, conservation of ground water enough with a cylindrical hole diameter of 10 cm. Benefits of biopore infiltration holes are reducing surface runoff, producing manure, fertilizing soil, reducing waste piles, and conserving ground water. The research objective was to analyze the cube biopore infiltration holes based on soil permeability, rainfall intensity, depth of groundwater level, and volume of organic waste. The results of the analysis can be obtained from the cube biopore infiltration holes which can absorb all the rainwater which can accommodate all organic waste. The results of permeability testing show that the average soil permeability is 0.00112 cm/s and the yield of maximum discharge runoff water in January is 97.57 cm3/second. The ground water level is two meters. While the volume of organic waste is one cubic per month. The result of the analysis showed that the area of cake absorption was 8.73 m2. When converted to a cube absorption field it takes approximately 8 meters wide by 0.5 meters and a depth of 0.5 meters. When divided into four cavity recharge holes LRB1 obtained area of 4 m2, LRB2 area of 2.7 m2, LRB3 area 2 m2, and LRB4 as reserve.

Application of hydrocyclone for separation of Pichia pastoris produced r-HBsAg from fermentation culture: impact of concentration and pressure on hydrocyclone performance

Separation of biomass from culture media by centrifugation and then washing the biomass are mandatory steps in the fermentation process of recombinant Pichia pastoris expressed HBsAg intracellularly. Biomass has to be washed many times to eliminate the culture media residues thoroughly. In this study, we tried to develop the hydrocyclone as an alternative method for separation of biomass from fermentation culture, an attractive replacement for centrifugation processes. The advantages of using hydrocyclone in biomass separation could be summarized in its suitability for continuous separation and its low risk of contamination. To evaluate the performance of hydrocyclone, concentration ratio in underflow to feed stream, capacity, and centrifugal force by considering three parameters of pressure drop, concentration, and the type of hydrocyclone were investigated.Using three level factorial design a concentration ratio equation was developed, with the correlation coefficient R2 = 0.977 ensured the good fitness of the predicted data with the experimental results. In optimal conditions, maximum concentration ratio was 1.246, for flow rate 13.5 LPM and C-force equal to 1276.11 at maximum pressure drop (3 bar) and minimum concentration (0.5% w/w) in hydrocyclone 1. Herein, two different hydrocyclones with the cylindrical diameters of 19 mm and 21 mm were used for separating the yeast cells.

Spiral Trajectory Modulation of Rheotaxic Motile Human Sperm in Cylindrical Microfluidic Channels of Different Inner Diameters.

We investigated the relationship between human sperm rheotaxis and motile sperm trajectories by using poly-(dimethylsiloxane) (PDMS)-based cylindrical microfluidic channels with inner diameters of 100 μm, 50 μm, and 70 μm, which corresponded to the inner diameter of the human isthmus, the length of a sperm and a diameter intermediate between the two, respectively. We counted the number of rheotaxic sperm and sperm with spiral motion. We also analyzed motile sperm trajectories. As the cylindrical channel diameter was decreased, the percentage of sperm cells exhibiting rheotaxis, the percentage of sperm cells exhibiting spiral motion, the frequency-to-diameter ratio of the sperm cells' spiral trajectories, and the surface area of the microfluidic channel increased, while the flagellar motion at the channel wall decreased. The percentage of sperm exhibiting a spiral trajectory and the frequency-to-diameter ratio of the sperm cells' spiral trajectories were thus affected by the channel diameter. Our findings suggest that the oviduct structure affects the swimming properties of sperm cells, guiding them from the uterus to the ampulla for egg fertilization. These results could contribute to the development of motile sperm-sorting microfluidic devices for assisted reproductive technologies.

Comparative investigation of small laccase immobilized on carbon nanomaterials for direct bioelectrocatalysis of oxygen reduction

In this study, different carbon nanomaterials (carbon nanotubes, solid carbon spheres and graphene nanosheets) for immobilizing bacterial small laccase (SLAC) to enable direct bioelectrocatalysis of oxygen reduction were comparatively investigated. Highest bioelectrocatalytic current response was achieved with ethanol-assisted SLAC adsorption on single-walled carbon nanotubes. Direct electron transfer (DET) rates were determined and generally shown to be larger with carbon nanomaterials in smaller dimensions or higher surface curvature, i.e., 1.92, 1.05, 1.52, 0.62 and 0.63 s−1 for adsorbed SLAC on single-walled carbon nanotubes (d = ca. 1.5 nm), double-walled carbon nanotubes (d = 2–4 nm), thinner multi-walled carbon nanotubes (d = 8–15 nm), thicker multi-walled carbon nanotubes (d = 20–30 nm) and graphene nanosheets, respectively. No obvious catalytic current response was obtained with solid carbon spheres (d > 200 nm). Surface nanostructures on electrodes with decreased cylindrical diameter could enable a favorable protein orientation of immobilized SLAC for efficient electronic communication between the catalytic copper sites and carbon nanomaterials as revealed by surface vibrational spectroscopy. Moreover, such a difference in DET kinetics of SLAC could be an outcome of synergic effects of surface properties (curvature, oxygen-containing groups, etc.) and conductivity of carbon nanomaterials. It is expected to offer useful information to fabricating carbon-based oxygen-reducing biocathodes of wide working pH range and high tolerance to chloride.

Preparation and characterization of size-controlled glioma spheroids using agarose hydrogel microwells.

Treatment of glioblastoma, the most common and aggressive type of primary brain tumors, is a major medical challenge and the development of new alternatives requires simple yet realistic models for these tumors. In vitro spheroid models offer attractive platforms to mimic the tumor behavior in vivo and have thus, been increasingly applied for assessment of drug efficacy in various tumors. The aim of this study was to produce and characterize size-controlled U251 glioma spheroids towards application in glioma drug evaluation studies. To this end, we fabricated agarose hydrogel microwells with cylindrical shape and diameters of 70–700 μm and applied these wells without any surface modification for glioma spheroid formation. The resultant spheroids were homogeneous in size and shape, exhibited high cell viability (> 90%), and had a similar growth rate to that of natural brain tumors. The final size of spheroids depended on cell seeding density and microwell size. The spheroids’ volume increased linearly with the cell seeding density and the rate of this change increased with the well size. Lastly, we tested the therapeutic effect of an anti-cancer drug, Di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT) on the resultant glioma spheroids and demonstrated the applicability of this spheroid model for drug efficacy studies.

Can one determine the density of an individual synthetic macromolecule?

Dendronized polymers (DPs) are large and compact main-chain linear polymers with a cylindrical shape and cross-sectional diameters of up to ∼15 nm. They are therefore considered molecular objects, and it was of interest whether given their experimentally accessible, well-defined dimensions, the density of individual DPs could be determined. We present measurements on individual, deposited DP chains, providing molecular dimensions from scanning and transmission electron microscopy and mass-per-length values from quantitative scanning transmission electron microscopy. These results are compared with density values obtained from small-angle X-ray scattering on annealed bulk specimen and with classical envelope density measurements, obtained using hydrostatic weighing or a density gradient column. The samples investigated comprise a series of DPs with side groups of dendritic generations g = 1-8. The key findings are a very large spread of the density values over all samples and methods, and a consistent increase of densities with g over all methods. While this work highlights the advantages and limitations of the applied methods, it does not provide a conclusive answer to the question of which method(s) to use for the determination of densities of individual molecular objects. We are nevertheless confident that these first attempts to answer this challenging question will stimulate more research into this important aspect of polymer and soft matter science.

Structure optimization of submerged water jet cavitating nozzle with a hybrid algorithm

ABSTRACTIt is critical to obtain a suitable geometry for a cavitating nozzle of submerged water jet, since a suitable geometry determines its cavitation intensity and cavitation distribution. This paper puts forward a water jet cavitating nozzle optimization platform aiming to improve its axial maximum vapor volume fraction. Considering the influence of all eight geometric parameters of the nozzle itself, a hybrid optimization algorithm is developed to optimize the nozzle by combining with the CFD technique. After the optimization, the optimal geometry results to a 9.41% increment in the axial maximum vapor volume fraction at 50 m underwater depth, and improves the cavitation effect obviously especially in deeper water. From the results, it is found that the cylindrical section diameter, contraction angle and diffusion angle have a great influence on the axial maximum vapor volume fraction, while the inlet diameter have the least effect on the same. The optimization presented in this study can lay the foundation for further study on water jet cavitating nozzle.

Meso-scale analyses of size effect in brittle materials using DEM

The paper describes numerical meso-scale results of a size effect on strength, brittleness and fracture in brittle materials like concrete. The discrete element method (DEM) was used to simulate the size effect during quasi-static splitting tension with the experimental-based meso-structure. The two-dimensional (2D) calculations were carried out on concrete cylindrical specimens with two diameters wherein two different failure modes occurred (quasi-brittle and very brittle with the snap-back instability). Concrete was modelled as a random heterogeneous 4-phase material composed of aggregate particles, cement matrix, interfacial transitional zones and macro-voids, based on x-ray micro-CT-images of the real concrete meso-structure. Attention was paid to the effect of the different specimen diameter on both the strength, brittleness and fracture pattern. Each internal energy component was analyzed in the fracture process zone and beyond it, and compared for the different post-peak behaviour of concrete. The evolutions of the number of broken contacts, coordination number, crack displacements and normal contact forces were also shown. Of specific interest was the fracture initiation and formation of two different failure modes. Next, the 2D DEM results of a size effect for 4 different specimen diameters were directly compared with corresponding experiments from the research literature. The experimental size effect was realistically reproduced in numerical calculations, i.e. the concrete strength and ductility decreased with increasing concrete specimen diameter. The calculated decreasing strength approached an asymptote with increasing cylindrical specimen diameter within the considered specimen size range.

17. Evaluation of MR and PET compatibility of dedicated radiotherapy positioning devices – a preliminary study

Purpose The aim of this preliminary study was to assess the compatibility of dedicated positioning devices developed for MR/PET imaging integration into radiotherapy planning. Methods The X-Tend Flat Table Top and specifically designed radiofrequency coil holders were tested on an integrated Biograph mMR MR/PET scanner (Siemens Healthcare). Magnetic field homogeneity and MR image quality in terms of artifacts and signal-to-noise ratio (SNR), with and without the radiotherapy positioning devices, were evaluated by means of a field sequence with 0.1 ppm/line and a clinical T2-weighted sequence, respectively. Acquisitions of a cylindrical (diameter 16 cm) doped (NiSO4) water phantom were performed by using a flexible 8-channel radiofrequency coil. SNR was estimated through the subtraction method. Since glass fiber table top and radiofrequency coil holders can attenuate PET signal, introducing potential quantification errors, PET photon attenuation was tested by the use of a cylindrical uniform phantom filled with 18-F and a sealed 68-Ge phantom. Also, a CT scan of the equipment was performed to calculate the transmission factor at 511 keV. Results The use of the dedicated radiotherapy positioning devices did not affect appreciably magnetic field homogeneity, and did not yield evident artifacts in T2-weighted images. When using the radiotherapy devices, SNR showed a reduction of less than 5% with respect to standard MR acquisitions. The average transmission factor of the radiotherapy table was computed to be around 90% from both CT scan and PET photon attenuation. Conclusions Based on our preliminary results, the dedicated radiotherapy positioning devices seem to be MR and PET compatible. Effect of radiotherapy devices on MR geometrical distortion and image uniformity, also for non-conventional quantitative diffusion-weighted imaging (a useful and sensitive tool for oncologic applications), are under evaluation. Further investigation is needed to assess the effect of radiotherapy table attenuation on PET contrast of lesions.

Characteristics of higher-harmonic breaking wave forces and secondary load cycles on a single vertical circular cylinder at different Froude numbers

A 3D numerical two-phase flow model based on solving Unsteady Reynolds-averaged Navier-Stokes (URANS) equations has been used to simulate spilling breaking waves past a single vertical cylinder installed at the edge of a 1:10 slope. The volume of fluid (VOF) method is employed to capture the free surface, and the k−ω Shear-Stress Transport (k−ω SST) turbulence model is used to simulate turbulence effects. Mesh and time-step refinement studies have been conducted by examining the free surface elevations in front of the cylinder and the total horizontal wave forces on the cylinder. These two quantities have also been compared with experimental data from Irschik et al. [21] to validate the present numerical model. The present numerical results are in good agreement with the measured data. The process of breaking waves past the cylinder is described and explained. Moreover, the ‘secondary load cycle’ phenomenon which may lead to higher-harmonic structural response is observed. The characteristics of higher-harmonic wave forces are discussed further at different Froude numbers by changing cylindrical diameters and incident wave properties for both breaking and non-breaking wave cases. For non-breaking wave cases, pronounced secondary load cycles are observed for the Froude number exceeding about 0.4, and the magnitudes of the secondary loads are about 8.1%–12.6% of the peak-to-peak wave force (crest to trough value). However, for breaking wave cases, the critical value of the Froude number to observe the pronounced secondary load cycles reduces to 0.35. The relative magnitude of the secondary load to the peak-to-peak wave force reduces to a range of 2.4%–7.6% due to the high slamming force. The duration of the secondary load cycle is not greater than 0.242T for all the cases, where T is incident wave period. For a vertical cylinder with a larger diameter, the pronounced secondary load cycle occurs with a larger wave steepness.

Effect of Binders on EFB Bio-briquettes of Fuel Calorific Value

The development of biomass has been assumed as an important issue in the past several decades and would remain to be attractive in the future due to its clean, renewable, and carbon–neutral properties. Biomass is one of the most important renewable energy resources in the world. In recent decades, the utilization of biomass has dramatically increased. There were many reasons. First, biomass is a renewable resource, because of the availability of biomass is unlimited, and its regenerative process runs well. Second, the extraction of biomass energy can be carried out more flexible. The biomass can be burned directly without high technology. Biomass bio-briquettes are often used as an energy source for cooking purpose and in some industries. The bio-briquettes are produced by densification of waste biomass using various processes. In this, the study manual densification of bio-briquettes was tested by three different binding agents; cassava flour, sago flour, and starch flour. The objective of this study was to compare different binding materials in the production of Empty Fruit Bunch (EFB) bio-briquettes between binders. The binder is used as a mixture on the EFB fiber. Three types of the binder are cassava flour, sago flour and starch flour are used as comparators to obtain high heating value. The percentage of binder in each sample is 2%. The ratio of the use of water as a diluent between the fiber and the adhesive is 1: 5. Samples of solid cylindrical shape diameter 4 cm and 5 cm high and density sample is 0.8 g/cm3. The pressure is used to generate samples specified in the mold volume. The volume of the cylinder is 62.8 cm3. The adhesive cassava with a percentage of 2% can provide power to the sample mechanically by a drop test at the height of 1.20 m. The result shows that the binder cassava has fuel calorific value average is 3661 cal/g, a binder of starch 3584 cal/g and sago 3537 cal/g. Results indicated that sample binder cassava flour has calorific fuel value higher than sago and starch flour.

An Anisotropic Elastic-plastic Model for the Optimization of a Press Machine’s Auxiliary Worktable Plate Thickness

In this work an anisotropic elastic–plastic finite element model strongly coupled with ductile damage is applied to determine the suitable thickness of added auxiliary worktable plate to a 100 ton maximum capacity press machine. The major focus of this study is to minimize the amount of stress transmitted to the optional worktable plate and the press machine body while allowing them to withstand plastic deformation and damage during compression testing until final sample fracture. The worktable plates and the press machine body are made of TRIP800 grade steel. AISI 316L stainless steel is chosen as test material for the cylindrical billets. The proposed model is based on a non-associative plasticity theory and the “Hill 1948” quadratic (equivalent) stress norm is considered to describe the large plastic anisotropic flow accounting for mixed isotropic and kinematic hardening with isotropic damage effect. For each material the model uses an experimental data base obtained from a set of tensile tests conducted until the final fracture in three directions, the rolling direction (RD) or 0, the transverse direction (TD) or 90, and the 45 direction. After several numerical simulations of compression testing using ABAQUS/Explicit FE® software, thanks to the user’s developed VUMAT subroutine, varying cylindrical billet diameters and material, worktable plates number and thicknesses and spatial plate configurations the solution of 100mm thick worktable plate is selected since in that case the cylinder specimen is totally damaged and the stress state inside the worktable plates and the press machine body remains admissible.

UTILIZATION OF RAWAPENING PEAT FOR NUTRIENT BLOCK AS A MEDIA NURSERIES Anthocephalus cadaba and Paraserianthes falcataria

Nutrient Block is a growing medium product in the form of a square (25 x 25 cm) or cylindrical (diameter = 20 cm, height = 25 cm) made of peat which has been composted, plus adhesive gypsum or tapioca waste. Nutrient Block is designed to support the post mining land rehabilitation program that is now threatening the environmental degradation in mining areas. Nutrient Block products has been proved good for growth because of the media in addition to having physical properties that are capable of storing large amounts of water, contain enough nutrients in the form available to plants,so it can support plant growth. Results of the Nutrient Block application test to Jabon (Anthocephalus cadaba) and Sengon (Paraserianthes falcataria) plants showed that good performance, both plant height and diameter of trees and leaf growth in plants Jabon appear healthy and getting wider.keywords: nutrient block, post-mining land rehabilitation. Paraserianthes falcataria, Anthocephalus cadaba

Two-point method uncertainty during control and measurement of cylindrical element diameters

The topic of the article is devoted to the urgent problem of the reliability of technical products geometric specifications measurements. The purpose of the article is to improve the quality of parts linear sizes control by the two-point measurement method. The article task is to investigate methodical extended uncertainties in measuring cylindrical element linear sizes. The investigation method is a geometric modeling of the element surfaces shape and location deviations in a rectangular coordinate system. The studies were carried out for elements of various service use, taking into account their informativeness, corresponding to the kinematic pairs classes in theoretical mechanics and the number of constrained degrees of freedom in the datum element function. Cylindrical elements with informativity of 4, 2, 1 and θ (zero) were investigated. The uncertainties estimation of in two-point measurements was made by comparing the results of of linear dimensions measurements with the functional diameters maximum and minimum of the element material. Methodical uncertainty is formed when cylindrical elements with maximum informativeness have shape deviations of the cut and the curvature types. Methodical uncertainty is formed by measuring the element average size for all types of shape deviations. The two-point measurement method cannot take into account the location deviations of a dimensional element, so its use for elements with informativeness less than the maximum creates unacceptable methodical uncertainties in measurements of the maximum, minimum and medium linear dimensions. Similar methodical uncertainties also exist in the arbitration control of the linear dimensions of the cylindrical elements by limiting two-point gauges.