Flat Disk Research Articles

Electrodynamic properties of solid solutions 0.98(xPbTiO3–yPbZrO3–zPbNb2/3Mg1/3O3)–0.02PbGeO3 in the microwave range

The behavior of samples of four-component solid solutions (SS) 0.98(xPbTiO3–yPbZrO3–zPbNb2/3Mg1/3O3)–0.02PbGeO3 in an electromagnetic field of the microwave range has been studied by the microstrip method. Dependences of frequency dispersion of the transmission coefficient, the reflection coefficient, and the degree of absorption of the material on PbTiO3 concentration have been analyzed. It has been found that the flat disk samples with the highest PbTiO3 concentration in the segment of the regular microstrip line have the widest absorption band (10 MHz ÷ 2.5 GHz).

Influence of temperature on the rheological behavior of industrialized honey

In the present work, the effect of temperature on the rheological properties of the industrialized honey of three different high-trade brands in the northern, central and southern Lima markets was studied. The physicochemical characteristics of water activity, specific gravity, moisture content, brix degrees, refractive index and pH were analyzed. No significant difference was found between the values ​​of the physicochemical properties within and between the groups of the commercial brands analyzed (p> 0.05). The industrialized honey was tested with a Brookfield RVDV-E concentric viscometer using a flat disk spindle at five temperature levels from 20 ºC to 60 ºC, and the influence of temperature with dynamic or absolute viscosity was studied. Through the rheogram, a behavior of a Newtonian fluid was observed. For all samples it was found that the mean absolute viscosity decreases with temperature at 20 ºC (7430 mPa∙s), 30 ºC (2636 mPa∙s), 40 ºC (955 mPa∙s), 50 ºC (440 mPa∙s) and 60 ºC (267 mPa∙s). The dependence of the viscosity with the temperature was described by a mathematical exponential model of three constants proposed in this investigation that gave a good fit, obtaining a coefficient of determination of 0.9999. The activation energy value calculated and within the temperature range tested was 68.73±0.129 kJ.mol-1. The results obtained in this study are of great interest to the industry that manipulates and formulates edible foods based on this type of product.

Curved accretion disks around rotating black holes without reflection symmetry

Rotating black holes without equatorial reflection symmetry can naturally arise in effective low-energy theories of fundamental quantum gravity, in particular, when parity-violating interactions are introduced. Adopting a theory-agnostic approach and considering a recently proposed Kerr-like black hole model, we investigate the structure and properties of accretion disk around a rotating black hole without reflection symmetry. In the absence of reflection symmetry, the accretion disk is in general a curved surface in shape, rather than a flat disk lying on the equatorial plane. Furthermore, the parameter epsilon that controls the reflection asymmetry would shrink the size of the prograde innermost stable circular orbits, and enhance the efficiency of the black hole in converting rest-mass energy to radiation during accretion. The retrograde innermost stable circular orbits are stretched but the effects are substantially suppressed. In addition, we find that spin measurements based on the gravitational redshift observations of the disk, assuming a Kerr geometry, may overestimate the true spin values if the central object is actually a Kerr-like black hole with conspicuous equatorial reflection asymmetry. The qualitative results that the accretion disk becomes curved and the prograde innermost stable circular orbits are shrunk turn out to be generic in our model when the reflection asymmetry is small.

In vitro culture of ovine embryos up to early gastrulating stages.

ABSTRACTDevelopmental failures occurring shortly after blastocyst hatching from the zona pellucida constitute a major cause of pregnancy losses in both humans and farm ungulates. The developmental events occurring following hatching in ungulates include the proliferation and maturation of extra-embryonic membranes – trophoblast and hypoblast – and the formation of a flat embryonic disc, similar to that found in humans, which initiates gastrulation prior to implantation. Unfortunately, our understanding of these key processes for embryo survival is limited because current culture systems cannot sustain ungulate embryo development beyond hatching. Here, we report a culture system that recapitulates most developmental landmarks of gastrulating ovine embryos: trophoblast maturation, hypoblast migration, embryonic disc formation, disappearance of the Rauber's layer, epiblast polarization and mesoderm differentiation. Our system represents a highly valuable platform for exploring the cell differentiation, proliferation and migration processes governing gastrulation in a flat embryonic disc and for understanding pregnancy failures during the second week of gestation. This article has an associated ‘The people behind the papers’ interview.

The people behind the papers - Priscila Ramos-Ibeas and Pablo Bermejo-Álvarez.

Symmetry breaking in ungulates occurs in a flat embryonic disc similar to that of humans, making it a potential model for studying early human development. However, it has previously been impossible to develop ungulate blastocysts in vitro to the symmetry-breaking stages. Now, a new paper in Development describes culture conditions that allow ungulate embryos to be developed in vitro through to early gastrulation. We caught up with corresponding authors, Priscila Ramos-Ibeas, Científico Titular at El Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), and Pablo Bermejo-Álvarez, Científico Titular at INIA, to find out more about their research and their future plans.

Clinical and radiological evaluation of cage subsidence following oblique lumbar interbody fusion combined with anterolateral fixation

BackgroundCage subsidence (CS) was previously reported as one of the most common complications following oblique lumbar interbody fusion (OLIF). We aimed to assess the impacts of CS on surgical results following OLIF combined with anterolateral fixation, and determine its radiological characteristics as well as related risk factors.MethodsTwo hundred and forty-two patients who underwent OLIF at L4-5 and with a minimum 12 months follow-up were reviewed. Patients were divided into three groups according to the extent of disk height (DH) decrease during follow-up: no CS (DH decrease ≤ 2 mm), mild CS (2 mm < DH decrease ≤ 4 mm) and severe CS (DH decrease > 4 mm). The clinical and radiological results were compared between groups to evaluate radiological features, clinical effects and risk factors of CS.ResultsCS was identified in 79 (32.6%) patients, including 48 (19.8%) with mild CS and 31 (11.8%) with severe CS. CS was mainly identified within 1 month postoperatively, it did not progress after 3 months postoperatively, and more noted in the caudal endplate (44, 55.7%). In terms of clinical results, patients in the mild CS group were significantly worse than those in the no CS group, and patients in the severe CS group were significantly worse than those in the mild CS group. There was no significant difference in fusion rate between no CS (92.6%, 151/163) and mild CS (83.3%, 40/48) groups. However, significant lower fusion rate was observed in severe CS group (64.5%, 20/31) compared to no CS group. CS related risk factors included osteoporosis (OR = 5.976), DH overdistraction (OR = 1.175), flat disk space (OR = 3.309) and endplate injury (OR = 6.135).ConclusionCS following OLIF was an early postoperative complication. Higher magnitudes of CS were associated with worse clinical improvements and lower intervertebral fusion. Osteoporosis and endplate injury were significant risk factors for CS. Additionally, flat disk space and DH over-distraction were also correlated with an increased probability of CS.

Shear Motion Characteristics Analysis of Electrorheological Fluids Between Flat Disk and Corrugated Disk

In order to improve the transmission torque caused by the electrorheological effect, a corrugated disk is proposed to replace traditional flat disk by changing the electrode surface shape. The new mechanism puts the device in a shear-squeeze mode of operation. Based on the constitutive equation of electrorheological fluids, the shear motion characteristics of the ER fluids between the flat disk and the corrugated disk are analyzed, including the pressure distribution, torque equations, and the comparison with double-flat-disk mechanism. The analysis shows that compared with the double-flat-disk structure, the flat-disk-corrugated-disk structure can enhance the transmitted torque over 2.6 times under the same operating parameters. The magnification of the torque is not related with the curve number of the corrugated disc, but mainly depends on the structural parameters of the device and corrugations, and the characteristic parameters of electrorheological fluid. It is proved that the mechanism can provide new ideas and new methods for the engineering application of electrorheological transmission technology.

Hydrothermal synthesis and electrochemical characterization of novel zeolite membranes supported on flat porous clay-based microfiltration system and its application of heavy metals removal of synthetic wastewaters

The present work describes the synthesis and characterization of a zeolite type LTA-clay composite membrane on pre-existing locally organized aluminosilicate in clay support and its application to the removal of heavy metals. X-ray diffraction reveals that the natural clay consists essentially of quartz, kaolinite, illite, dolomite, and calcite phases. Flat discs, membrane supports are prepared by uniaxial pressing of natural clay with 160 ≤ Ф < 250 μm as optimal grain size mixed with 3% w/w activated carbon as porogen agent. Membrane supports are consolidated by sintering to final temperatures of 1000 °C. Zeolite Linde type A (LTA) is deposited on the clay supports using the hydrothermal method. Nitrogen adsorption analysis of the support using Brunauer–Emmett–Teller (BET) theory showed pores with 35.5 nm, which is narrowed to 14.2 nm after zeolite-A deposition. X-ray analysis of the composite membrane (MZA) reveals the growth of new diffraction peaks characteristic of zeolite-A. Prior to water filtration analysis of the MZA composite membrane, the pzc is found to be 9.8 using the titration method. The efficiency of the MZA composite membrane is evaluated by filtration tests of solutions containing heavy metals using a flow loop developed specifically for dead-end filtration. The retention of heavy metals studied follows the order Pb 2+ > Al 3+ > Co 2+ > Cd 2+ > Zn 2+ with 99.7, 99, 89.5, 88.3 and 81.8 retention percent, respectively. The retention mechanism seems to be controlled by the charge of the membrane's surface, which is demonstrated using the linear wave anodic stripping voltammetry (LWASV). • Composite membrane (MZA) is prepared from a natural clay and deposited zeolite A. • Pores' structures and surface properties of the MZA affect the filtration performance. • Pre-existing locally organized aluminosilicate in the clay support enhances the crystallinity of zeolite A. • Selectivity of the MZA towards filtered ions is investigated by linear wave anodic stripping voltammetry. • Retention of heavy metals on MZA reaches 99.7%, 99%, 89.5%, 88.3%, 81.8% for Pb 2+ , Al 3+ , Co 2+ , Cd 2+ and Zn 2+ respectively.

Экспериментальное исследование и численное моделирование метания алюминиевого образца для магнитно-импульсной сварки

The induction acceleration method is quite widely used in impact experiments with conductive disks. The paper presents an experimental study and numerical simulation concerning magnetic pulse acceleration of thin flat discs made of D16AM aluminium alloy. We used a flat copper coil and a capacitor power source to investigate magnetic pulse welding possibilities. The high-energy pulse method is efficient, safe, capable of precisely setting pulse discharge power by varying the capacitor (energy storage) capacitance and voltage, while heating the work piece with induced current can lead to an increase in its plasticity. We used the LS-DYNA finite element analysis software package to run our numerical simulation. The results obtained show that there is a significant disadvantage to using this acceleration setup: it is difficult to ensure that the sample accelerated remains planar.

Acoustic Performance of a Metascreen-Based Coating for Maritime Applications

Abstract Time- and frequency-domain numerical models are developed to investigate the acoustic performance of metascreen-based coatings for maritime applications. The coating designs are composed of periodic air-filled cavities embedded in a soft elastic medium, which is attached to a hard backing and submerged in water. Numerical results for an acoustic coating with cylindrical cavities are favorably compared with analytical and experimental results from the literature. Frequencies associated with peak sound absorption as a function of the geometric parameters of the cavities and material properties of the host medium are predicted. Variation in the cavity dimensions that modifies the cylindrical-shaped cavities to flat disks or thin needles is modeled. Results reveal that high sound absorption occurs when either the diameter or length of the cavities is reduced. Physical mechanisms governing sound absorption for the various cavity designs are described.

(Dis)connectedness of nonlocal minimal surfaces in a cylinder and a stickiness property

We consider nonlocal minimal surfaces in a cylinder with prescribed datum given by the complement of a slab. We show that when the width of the slab is large the minimizers are disconnected and when the width of the slab is small the minimizers are connected. This feature is in agreement with the classical case of the minimal surfaces. Nevertheless, we show that when the width of the slab is large the minimizers are not flat discs, as it happens in the classical setting, and, in particular, in dimension 2 2 we provide a quantitative bound on the stickiness property exhibited by the minimizers. Moreover, differently from the classical case, we show that when the width of the slab is small then the minimizers completely adhere to the side of the cylinder, thus providing a further example of stickiness phenomenon.

Tracing Accretion onto Herbig Ae/Be Stars Using the Brγ Line

Abstract Accretion plays an important role in protoplanetary disk evolution, and it is thought that the accretion mechanism changes between low- and high-mass stars. Here we characterize accretion in intermediate-mass, pre-main-sequence Herbig Ae/Be (HAeBe) stars to search for correlations between accretion and system properties. We present new high-resolution, near-infrared spectra from the Immersion GRating INfrared Spectrograph for 102 HAeBes and analyze the accretion-tracing Brγ line at 2.166 μm. We also include the samples of Fairlamb et al. and Donehew &amp; Brittain, for a total of 155 targets. We find a positive correlation between the Brγ and stellar luminosity, with a change in the slope between the Herbig Aes and Bes. We use L Brγ to determine the accretion luminosity and rate. We find that the accretion luminosity and rate depend on stellar mass and age; however, the trend disappears when normalizing the accretion luminosity by the stellar luminosity. We classify the objects into flared (group I) or flat (group II) disks and find that there is no trend with accretion luminosity or rate, indicating that the disk dust structure is not impacting accretion. We test for Brγ variability in objects that are common to our sample and previous studies. We find that the Brγ line equivalent width is largely consistent between the literature observations and those that we present here, except in a few cases where we may be seeing changes in the accretion rate.

MOVEMENT OF THE PARTICLE ON THE EXTERNAL ROUGH SURFACE OF THE CONE WHICH ROTATES AROUND THE VERTICAL AXIS

In machines that work with technological material, which consists of individual particles, there is an interaction of these particles with the rough surfaces of the working bodies. The working bodies can be stationary or perform various movements. The determination of the kinematic characteristics of particle movement has its own characteristics, which depend on the shape, design parameters of the working bodies, the nature of the interaction with the technological material, the properties of the material and so on. It is important to know the patterns of this interaction, as it helps to improve the design of the executive bodies of machines. The paper considers the relative movement of a particle on the outer rough surface of a cone rotating around a vertical axis with a given angular velocity. The formula for finding the limiting value of the angular velocity, which depends on the angle of inclination of the generatrices, the coefficient of friction and the distance from the top of the cone to the particle, is found. It is also valid for a flat disk, for the case when the angle of inclination of the generatrices is equal to zero. Differential equations of movement of particles in projections on the axis of a fixed coordinate system are compiled, which are solved by numerical methods. The initial velocity of the particle at the moment of hitting the surface of the cone after falling from a certain height is taken into account. The relative trajectories of the particle sliding along the surface of the cone are constructed, as well as the absolute trajectories of its movement with respect to the fixed coordinate system. Visualization of kinematic characteristics is presented. The material considered in the article takes place in sowing machines, in which the seeds fall on a rotating cone.

Impact ice adhesion strength of stainless steel 304 as determined on a centrifuge test stand

Passive approaches to mitigate accreting ice on aircraft while in-flight (i.e., impact ice) using coatings are actively being investigated. Determination of impact ice adhesion under simulated in-flight conditions however is dependent upon the test method. Tests that slowly form ice (i.e., freezer ice) may not accurately simulate in-flight icing (i.e., impact icing) conditions where supercooled water droplets impact a surface at a particular velocity. The Adverse Environment Rotor Test Stand (AERTS) located at the Pennsylvania State University (PSU) is one facility that has demonstrated simulation of impact icing conditions for determination of ice adhesion strength (τ) without sample removal from the ice accretion environment. This facility though is in high demand requiring a significant amount of lead time and capital to obtain τ results neither of which is conducive to exploratory research. As a solution for quick and economic screening of materials in a controlled manner under simulated impact icing conditions, a laboratory-scale ice adhesion test device (AERTS Jr.) was developed by PSU based on the AERTS design under funding from NASA Langley Research Center. To verify operation, a study was conducted using flat stainless steel 304 disks having surface roughness values ranging from 172 to 662 nm as determined by optical profilometry. Tests were conducted under impact icing conditions from −16 to −8 °C with supercooled water droplets having a median volume diameter of 20 μm that afforded an icing cloud with a liquid water content of approximately 0.30 g/m3 within the device. For each substrate roughness evaluated, a linear relationship with a correlation coefficient of > 0.97 was obtained for plots of τ vs temperature that followed the known trend of decreasing temperature and increasing τ. Plots of τ vs surface roughness also followed the known linear trend of increasing τ with increasing surface roughness at each test temperature. Statistical analysis found that for surfaces of comparable roughness τ was similar. The τ at −8 °C obtained on AERTS Jr. was comparable to those obtained for flat disks on AERTS Jr. II, a second generation AERTS Jr. developed for NASA Glenn Research Center, based on calculated values.

Enhancement of discs’ solar still performance using thermal energy storage unit and reflectors: An experimental approach

In this study, new rotating discs solar still (SS) has been investigated with different discs’ configurations, thermal energy storage unit (TESU) and employing external reflectors. Three shapes of rotating discs (flat, finned and corrugated) have been studied at constant rotational speed of 0.1 rpm. Four rotating discs are used on the back and side walls of the discs SS to increase the evaporation surface area of water and the exposed area to solar energy. The results showed that finned discs are the best for SS performance when compared with flat and corrugated discs. The improvement in productivity is 68%, 86% and 106% over the conventional SS for flat, corrugated and finned discs SS (FDSS), respectively. When employing TESU (Paraffin wax mixed with CuO nanoparticles) with emerging fins, the FDSS productivity showed 149% increase in productivity over the conventional SS. For further enhancement in FDSS productivity, external reflectors are utilized, where the productivity of FDSS with TESU and reflectors showed 184% productivity rise over the conventional SS. The thermal efficiency of the flat discs SS, corrugated discs SS, FDSS, FDSS-TESU and FDSS-TESU-reflectors is 44.5, 47, 50, 56.5 and 51.3%, respectively. The estimated costs per liter of produced freshwater from conventional SS and FDSS-TESU-reflectors are 0.024 and 0.014 $, respectively.

Treatment of Inguinal Hernia with Tension-free Filling and Tension-free Flat Disc Hernia Repair and Its Clinical Effect

Treatment of Inguinal Hernia with Tension-free Filling and Tension-free Flat Disc Hernia Repair and Its Clinical Effect

Numerical and Experimental Studies on Hydro-Forming of a Thin Metallic Disc

This paper deals with the hydro-forming of a flat thin metallic disc to achieve a forward domed disc which will be subsequently adopted to manufacture a rupture disc. The plastic deformation induced by the hydraulic energy is numerically simulated through an isotropic hardening plasticity model using a non-linear explicit finite element analysis (FEA). The variation in disc’s central deformation, thickness, equivalent plastic stress and equivalent plastic strain with respect to the applied hydraulic pressure are determined from FEA simulations. The hydro-forming setup is then designed and manufactured, and the metallic disc is experimented under hydro-forming process. The reduction in thickness due to stretching of the thin disc is evaluated from experiment and simulation and a close agreement is found. This research attempt helped in finalizing the hydro-forming fluid pressure, the feasibility and the accuracy of practically achieving the desired geometry of the metallic disc. The near-fixidity effects on abrupt variation in sheet thickness and plastic strain are well captured through simulations which are very difficult to be studied through hydro-forming experiments.

Optimizing the adhesion of soil-touching parts based on biomimetic concepts using the Taguchi method

Several studies highlighted that the surface shape modifications which are inspired by the soil-burrowing animals have positively impacted the soil-tool adhesion; however, it is still unclear what the optimum dimensions of the domed surface are for minimizing soil-tool adhesion. In this study, twenty-seven domed discs were created according to Taguchi orthogonal array L27(33) to determine the optimum dimensions of the domed surface that minimize normal adhesion force and disc sinkage simultaneously, as well as comparing the effect of the optimized domed disc versus the flat disc on the normal adhesion force under different soil conditions. The results revealed that disc coverage ratio and dome height to diameter ratio are essential to design parameters that influence the normal adhesion force of discs. According to the signal-to-noise ratio analysis, it was observed that the combination of 60% disc coverage ratio, 25% dome height to diameter ratio, and 10 mm dome base diameter was found to be the most appropriate for the well-balanced improvement of both normal adhesion force and disc sinkage simultaneously. In all treatments, the optimized domed disc produced less normal adhesion force than the flat disc (about 7%-18%, according to soil condition). It can be concluded that properly designed domed surfaces can significantly reduce the normal adhesion force when compared to flat surfaces. Keywords: biomimetics, paddy soil, normal adhesion, disc sinkage, Taguchi method DOI: 10.25165/j.ijabe.20221501.6147 Citation: Salem A E, Zhang G Z, Abdeen M A M, Wang H C, Gao Y. Optimizing the adhesion of soil-touching parts based on biomimetic concepts using the Taguchi method. Int J Agric & Biol Eng, 2022; 15(1): 147–154.

Macroscopic Disk Rotation by Means of Surface Acoustic Waves.

It is shown experimentally that a flat piezoelectric disk poled perpendicular to its surface and suspended on a thin thread can be rotated about 50° by two surface acoustic waves (SAWs) intentionally excited with different amplitudes and propagating in the opposite directions. The excitation of such counter-propagating SAWs with different amplitudes is based on the nonsymmetrical interdigital transducer with different angular width electrodes located along the disk radius. The angular width of each of the two electrodes per angular period is not change along the disk radius. Such a ring unidirectional transducer realized on one of the disk surfaces is used for the excitation of SAWs. Hereby, the flat surface of the disk allows one to create any transducer pattern using conventional technology. The other disk surface can be free or covered by the silver layer.

In Ovo Gain- and Loss-of-Function Approaches to Study Gut Morphogenesis.

The polarity of cellular components is essential for cellular shape changes, oriented cell migration, and modulating intra- and intercellular mechanical forces. However, many aspects of polarized cell behavior-especially dynamic cell shape changes during the process of morphogenesis-are almost impossible to study in cells cultured in plastic dishes. Avian embryos have always been a treasured model system to study vertebrate morphogenesis for developmental biologists. Avian embryos recapitulate human biology particularly well in the early stages due to their flat disc gastruloids. Since avian embryos can be manipulated in ovo they present paramount opportunities for highly localized targeting of genetic mechanisms during cellular and developmental processes. Here, we review the application of these methods for both gain of function and loss of function of a gene of interest at a specific developmental stage during left-right (LR) asymmetric gut morphogenesis. These tools present a powerful premise to investigate various polarized cellular activities and molecular processes in vivo in a reproducible manner.