Hollow Axis Research Articles

Device for automation of hydrostatic leveling of man-made structures with alternative power supply

The article discusses the issue of ensuring the reliability, durability, and safety of buildings and engineering, including hydraulic structures, by creating an automated hydrostatic leveling system with a device that uses fiber optics combined with an LED and a photodetector, installed on one hollow axis of rotation of the drum, like a sensor a ferromagnetic transducer was used for the displacement pulse, a comparative analysis of the existing means for measuring settlements and deformations of objects using laser and photoelectric means was carried out. A patented device has been developed that provides high accuracy, reliability, and the ability to create a monitoring system with remote information delivery with an autonomous energy source. The device can be used to install and assembly conveyor lines in determining the vertical deformations of dams, buildings, and structures during operation.

Perovskite Crystallization Dynamics during Spin-Casting: An In Situ Wide-Angle X-ray Scattering Study.

In situ wide-angle X-ray scattering (WAXS) has been measured during the spin coating process used to make the precursor films required for the formation of thin films of perovskite. A customized hollow axis spin coater was developed to permit the scattered X-rays to be collected in transmission geometry during the deposition process. Spin coating is the technique most commonly used in laboratories to make thin perovskite films. The dynamics of spin-casting MAPbI3–xClx and FAPbI3–xClx films have been investigated and compared to investigate the differences between the dynamics of MAPbI3–xClx and FAPbI3–xClx film formation. In particular, we focus on the crystallization dynamics of the precursor film formation. When casting MAPbI3–xClx, we observed relatively fast 1D crystallization of the intermediate product MA2PbI3Cl. There was an absence of the desired perovskite phase formed directly; it only appeared after an annealing step that converted the MA2PbI3Cl to MAPbI3. In contrast, slower crystallization via a 3D precursor was observed for FAPbI3–xClx film formation compared to MAPbI3–xClx. Another important finding was that some FAPbI3–xClx perovskite was generated directly during spin-casting before annealing. These findings indicate that there are significant differences between the crystallization pathways for these two perovskite materials. These are likely to explain the differences in the lifetimes of the resulting perovskite solar cell devices produced using FA and MA cations.

Influence of TiO2 layer on ultimate efficiencies for planar and nano-textured CH3NH3PbI3 solar cells

The influence of TiO2 layer on the ultimate efficiencies, η, i.e. efficiencies without considering carrier recombination, for the planar and nano-textured CH3NH3PbI3 (MAPbI3) perovskite solar cells (SCs) are investigated. In planar TiO2/MAPbI3 heterojunction SCs, in order to achieve the largest power conversion efficiency (PCE), the TiO2 layer thickness, d1, is important. With the finite difference time domain (FDTD) method, we demonstrated that when the MAPbI3 layer thickness, d2, is 250 nm, which is a common-most MAPbI3 layer thickness for perovskite SCs, η achieves maximum when d1 is 80 nm. Fabricating nano textures on SC surface is an important method to improve the PCE. We studied the effects of d1 and d2 on the optimized η, η0, for two kinds of nano-textured perovskite SCs: the SCs with the nontextured TiO2 layer and the column-shaped nano hollow (CLH) textured MAPbI3 layer, defined as the nontextured-TiO2/CLH-MAPbI3 SCs, and the SCs with CLH textured TiO2 and CLH textured MAPbI3 layers of the same hollow axes and radius, defined as the CLH-(TiO2/MAPbI3) SCs. Generally, when d1 and d2 are fixed, η0 for the CLH-(TiO2/MAPbI3) SC is larger than that for the nontextured-TiO2/CLH-MAPbI3 SC by ca. 5%.

Forecasting the durability of hollow shafts and axles of agricultural machinery products

The issues of increasing durability in the development of technologies for strengthening the critical parts of agricultural machinery products are considered. The conducted experiments and calculations show that the use of hollow axes, shafts and other hollow products gives a great technical and economic effect, reduces the consumption of metal, facilitates the weight of equipment and ensures its high performance. The technique of prediction of the durability of parts with thermomechanical processing and deformation by screw compression from hot-rolled especially thick-walled pipes is presented, their bench and operational tests have been carried out, showing that hardened hollow parts not only do not concede, and sometimes exceed continuous durability. Optimization of the processing of parts, taking into account the stated results of theoretical and experimental studies, makes it possible to increase their efficiency. Considering that it is necessary to deal with multifactorial dependencies, it is advisable to automate their solution. Algorithms and programs for computer technology have been developed for a number of technological processes, successfully used both for automating the design of technological processes and for automating production itself. With the use of thermomechanical processing and deformation by screw compression, a fivefold increase in durability with asymmetric sign-constant bending is achieved on some products (track fingers of caterpillar machines). Thus, it becomes evident that the use of hollow axes, shafts and other hollow parts in agricultural machinery construction is much more widespread than at present, given the very important property of these hollow parts, that they are less sensitive to stress concentration under cyclic loads, especially if hardening is performed by high-temperature thermomechanical processing. It is recommended to use this unique treatment of responsible and highly loaded machine parts for a wide range of applications.

Fatigue crack growth life prediction of railway hollow axis with flaws under press fitting and measured dynamic stress spectrum

Damage tolerance analysis and residual life of the train hollow axis at the speed of 385 km/h were conducted with measured stress spectrum and press fits of wheel-axle and gear-axle in the framework of linear elastic fracture mechanics by 20-node isoparametric singular element in the close vicinity of crack tip. For this purpose, a postulated semi-elliptical surface crack with an initial depth of 2 mm was inserted into the shaft shoulder, wheel-axle pressing area, wheel-gear transition zone, gear-axle pressing area and axle body, respectively. Numerical simulation shows that the fatigue cracking lives of wheel-gear release groove, shaft shoulder, wheel-axle pressing area, and gear-axle pressing zone are approximately 79, 587, 8239 and 3725 thousand kilometers, respectively. Due to a typical compressive stress near the middle of axis body, it is identified that the crack is arrested. Research results provide important theoretical basis and scientific support for the safety design and reliable service of the hollow axle of next generation China high-speed train.

Predicting shallow landslide size and location across a natural landscape: Application of a spectral clustering search algorithm

Predicting shallow landslide size and location across landscapes is important for understanding landscape form and evolution and for hazard identification. We test a recently developed model that couples a search algorithm with 3-D slope stability analysis that predicts these two key attributes in an intensively studied landscape with a 10 year landslide inventory. We use process-based submodels to estimate soil depth, root strength, and pore pressure for a sequence of landslide-triggering rainstorms. We parameterize submodels with field measurements independently of the slope stability model, without calibrating predictions to observations. The model generally reproduces observed landslide size and location distributions, overlaps 65% of observed landslides, and of these predicts size to within factors of 2 and 1.5 in 55% and 28% of cases, respectively. Five percent of the landscape is predicted unstable, compared to 2% recorded landslide area. Missed landslides are not due to the search algorithm but to the formulation and parameterization of the slope stability model and inaccuracy of observed landslide maps. Our model does not improve location prediction relative to infinite-slope methods but predicts landslide size, improves process representation, and reduces reliance on effective parameters. Increasing rainfall intensity or root cohesion generally increases landslide size and shifts locations down hollow axes, while increasing cohesion restricts unstable locations to areas with deepest soils. Our findings suggest that shallow landslide abundance, location, and size are ultimately controlled by covarying topographic, material, and hydrologic properties. Estimating the spatiotemporal patterns of root strength, pore pressure, and soil depth across a landscape may be the greatest remaining challenge.

Metal-Organic Frameworks Incorporating Various Alkoxy Pendant Groups: Hollow Tubular Morphologies, X-ray Single-Crystal Structures, and Selective Carbon Dioxide Adsorption Properties.

Eight porous metal-organic frameworks (MOFs) incorporating various alkoxy pendant groups (-OC(n)H(2n+1); n=1-8) in the channels have been synthesized. All MOFs have macrosized, hollow, single-crystal morphologies independent of the type of alkoxy pendant groups. The X-ray single-crystal structures indicate that the MOFs have doubly interpenetrated 3D frameworks that generate clover-shaped 1D channels, the window sizes of which reduce as the length of the alkoxy pendant groups increases from -OCH3 to -OC8H17. The hollow axes of the tubular crystals are parallel to the 1D channels of the MOFs, which suggests that the hollow crystal is grown by the unidirectional addition of pillar ligands to the 2D network. Among the activated MOFs, only the MOFs with methoxy and ethoxy pendant groups show selective CO2 adsorption over N2 and CH4, whereas those with longer alkoxy pendant groups barely adsorb CO2 at room temperature, which implies that the pendant doors of the MOFs should have an appropriate length for selective CO2 capture.

TENSIONES EN EJES HUECOS CON UNA GRIETA SUPERFICIAL BAJO FLEXIÓN ROTATIVA

ABSTRACT: Hollow axis are widely used in all branches of industry and bear great responsibility. Their behaviour under fatigue being nonetheless well known, and the crack growth phenomenon extensively studied, the understanding of the physical phenomenon somewhat lacks theoretical backing. The present paper gives a start to the theoretical study of the stresses in a hollow axis in flexural mode, considering the variations of its strength moment and its nominal tractive efforts, showing that these endure oscillations harsher than those usually attributed to these cases. Keywords: Fatigue, hollow axis, cracks, bending and rotation, analytical study

FDTD modelling in high‐resolution 2D and 3D GPR surveys on a reinforced concrete column in a double wall of hollow bricks

A structural characterization of a reinforced concrete column in a double wall of hollow bricks, carried out within diagnostics testing through 2D and 3D high‐frequency GPR surveys and aimed at the evaluation of the seismic vulnerability of a building is proposed. It highlights how the use of FDTD simulation allows the limits of these surveys to be overcome, with reference to the difficulty of the processing and interpretation steps in order to identify rebars beyond the hollow bricks. Their reflection pattern, being complex, makes it very hard to recognize the rebars placed parallel to the brick hollow axis direction.

A morphological and molecular assessment of the genus Sinotubimorpha (Halymeniaceae, Rhodophyta)

Abstract A critical reassessment of the morphological features of two closely related red algal genera, Grateloupia C. Agardh and Sinotubimorpha W. X. Li & Z. F. Ding (Halymeniaceae), pointed out that members of the two genera had most morphological characteristics in common, including the Grateloupia type auxiliary cell ampullae. Sinotubimorpha hitherto was distinguished from Grateloupia by: (i) the hollow axis; (ii) the presence of secondary filaments in ampullae; (iii) 1- to 3-celled carpogonial branch; and (iv) the occasional production of 1- to 4-celled flanking filaments on carpogonium. However, when these features were re-examined among 37 Chinese species of genera described in Flora Algarum Marinarum Sinicarum and one newly reported species, Grateloupia orientalis, we found that it was difficult to draw a clear-cut distinction between the two genera based only on morphological differences. In rbcL sequence analysis, all the species of Sinotubimorpha with G. catenata formed a single monophyletic subclade within the large Grateloupia clade of the Halymeniaceae. It is therefore suggested that all the Chinese species of Sinotubimorpha, S. catenata, S. guangdongensis, S. qingdaoensis, S. claviformis, and S. ramosissima should be synonymous with G. catenata, and that Sinotubimorpha should be included in synonymy under Grateloupia.

A Swing Arc System for Narrow Gap GMA Welding

A novel swing arc system was developed to realize high quality narrow gap GMA welding at low cost. This system uses a motor of hollow axis to turn directly the micro-bent conductive rod and then to weave circularly the arc around itself axis of torch, and can automatically search for the midpoint of symmetrical swing trail and detect precisely swing frequency in real time. Three mathematical models are also presented to calculate precisely key swing variables from torch structure and process parameters. Experimental results show that weld surface curvature and the penetration into groove sidewalls increase and weld sectional thickness decreases with increasing swing frequency and at-sidewall staying time of arc, while bottom shape of bead varies from single to twin peaks. This swing arc process thus improved obviously narrow gap weld formation.

A study on submerged rotating MBR for wastewater treatment and membrane cleaning

A submerged rotating membrane bioreactor (SRMBR), with a rotatable, rounded, flat-sheet Poly(vinyldiene fluoride) (PVDF) membrane module fixed on hollow axes and moved by an electromotor, was used for wastewater reclamation. It was found that the effluent COD became stable and lower than 20 mg/L after one day running. The equilibrium permeate flux increased from 42.5 to 47.5 L/m2·h with the rotation speed increasing from 15 r/min to 25 r/min. Prolonging relaxation time could alleviate membrane fouling and enhance the flux. Finally, membrane cleaning was studied. The results showed that flushing the membrane surface with water, water/NaOH and water/NaOH/HCl recovered permeate flux to 48.4%, 83.5% and 90.2% of that of the initial operation, respectively.

Novel rotation arc system for narrow gap MAG welding

The present paper develops a hollow axis motor driven high speed rotation arc system for narrow gap welding (NGW), and introduces the features of this system. Some welding experiments were then carried out to investigate the characteristics of welding wire melting and weld formation for this new process. Experimental results show that the melting rate of wire increases and the residual melting ball diameter of wire tip decreases respectively with an increase in rotation speed, and this melting rate is higher in pulsed welding and NGW respectively than in dc and flat plate welding. Furthermore, the arc rotation can obviously improve the penetration into NGW groove sidewalls and bead shape, and thus the system has been used to weld practical NGW joints successfully.

Simulated effect of a forest road on near‐surface hydrologic response: redux

AbstractIn the work reported here the comprehensive physics‐based Integrated Hydrology Model (InHM) was employed to conduct both three‐ and two‐dimensional (3D and 2D) hydrologic‐response simulations for the small upland catchment known as C3 (located within the H. J. Andrews Experimental Forest in Oregon). Results from the 3D simulations for the steep unchannelled C3 (i) identify subsurface stormflow as the dominant hydrologic‐response mechanism and (ii) show the effect of the down‐gradient forest road on both the surface and subsurface flow systems. Comparison of the 3D results with the 2D results clearly illustrates the importance of convergent subsurface flow (e.g. greater pore‐water pressures in the hollow of the catchment for the 3D scenario). A simple infinite‐slope model, driven by subsurface pore‐water pressures generated from the 3D and 2D hydrologic‐response simulations, was employed to estimate slope stability along the long‐profile of the C3 hollow axis. As expected, the likelihood of slope failure is underestimated for the lower pore pressures from the 2D hydrologic‐response simulation compared, in a relative sense, to the higher pore pressures from the 3D hydrologic response simulation. The effort reported herein provides a firm quantitative foundation for generalizing the effects that forest roads can have on near‐surface hydrologic response and slope stability at the catchment scale. Copyright © 2006 John Wiley & Sons, Ltd.

Reinstatement of Grateloupia catenata (Rhodophyta, Halymeniaceae) on the basis of morphology and rbcL sequences

Morphological observations and molecular analysis of a red alga, which has been known as Grateloupia filicina var. lomentaria, G. filicina var. porracea f. lomentaria, or Sinotubimorpha porracea (Cryptonemiales, Halymeniaceae) in the western Pacific, were made for field-collected and cultured plants. The auxiliary-cell ampullae lack tertiary filaments and are of the Grateloupia-type. Morphologically, this alga can be distinguished from G. filicina by (1) the hollow axis; (2) the numerous short proliferations with Lomentaria-like constrictions that densely cover the surface of erect axes in mature plants; and (3) a tendency for reproductive structures to be restricted to the proliferations. The presence of 4.2–4.6% (62–67 bp) nucleotide substitutions in the ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbcL) between G. filicina and the alga in question also strongly supports the differentiation of these two entities at the species level. The form of the proliferations distinguishes the alga in question from the West Indies G. porracea. Re-examination of type material of Grateloupia catenata Yendo, which has been placed into synonymy under Grateloupia filicina var. porracea f. lomentaria, revealed that our freshly collected specimens matched it, and therefore the Yendo name is reinstated. The topological position of Grateloupia catenata in rbcL trees does not support its separation from other Grateloupia species at the generic rank.

Spatial Distribution of Radiant Intensity from Primary Sources for Atomic Absorption Spectrometry. Part I: Hollow Cathode Lamps

The spatial distribution of radiant intensity from hollow cathode lamps used as radiation sources in atomic absorption spectrometry is investigated with a digital photodiode array imaging system. Intensity distribution over the cross section of each lamp is measured for both atomic and ionic lines of the analyte and the filler gas. The shape of the distribution is strongly dependent on the hollow cathode diameter. In small cathodes the distribution has the shape of a paraboloid with maximum intensity at the hollow cathode axis for all of the recorded lines. The intensity distributions of lines emitted from large cathodes are nonparaboloid and in some cases have a minimum at the cathode axis and a maximum concentric to the cathode walls. It is shown that the intensity distribution for a given lamp has practically the same shape for all currents applied. Data on the evolution of the intensity distribution during warm-up of the lamps and under various operating conditions are presented.

Hydrologic Processes in a Low‐Gradient Source Area

Discharge, piezometric, and other field observations from a 3‐year monitoring program indicate that runoff from a low‐gradient source area in Marin County, California, is controlled by the interaction of throughflow, macropore flow, and saturation overland flow. Throughflow response integrates multiple storm events and exhibits both seasonal trends and rapid response to midwinter storms upon saturation of highly conductive near‐surface soils. After saturation of the deeper colluvium along the hollow axis, macropore flow responds rapidly to individual storm events and locally provides a ceiling to piezometric response. Saturation overland flow occurs along the axis of the unchanneled valley only during large storms when both soil matrix and macropore transmissivity are exceeded. During large, runoff‐producing storms, saturation overland flow extends continuously over most of the unchanneled valley axis. During smaller runoff‐producing events, however, ground surface saturation may be discontinuous, reflecting either variations in the conductivity of the underlying soil/bedrock or a variable soil thickness along the hollow axis. Results of this study document a sequence of flow path activation in which the temporal distribution of rainfall events within a season determines both the mechanism and magnitude of runoff generation.

Subsurface hydrology of layered colluvium mantles in unchannelled valleys—south‐Eastern Brazil

AbstractThe effects of subsurface hydrology on the evolution of erosive processes inside layered colluvium mantles in unchannelled valleys are investigated. Tensiometer nests are installed in different morphological conditions with their specific depths controlled by the subsurface structure of the colluvium mantle. Daily readings (during one year) and physical and mechanical analyses of the different colluvium layers are carried out.In spite of a highly discontinuous subsurface structure, present topography is the major factor controlling subsurface flow in this landscape. Paleotopographic features, usually resulting from the lateral mobilization of the previous topographic hollow axis, can locally control the preferential expansion of the saturated zone towards areas other than the present hollow axis. During rainy periods, pressure head at the base of the hollow axis increases towards a maximum value which is not increased by subsequent precipitation inputs. New water input is dissipated by direct precipitation onto the saturated zone and exfiltration by seepage at the gully head walls, precluding the development of the excess pore pressures required to trigger failure by landsliding.

Erosion of Thin Foils by Sputtering in Hollow Cathodes

Abstract A thin copper foil placed diagonally in a cylindrical copper hollow cathode undergoes fast erosion caused by cathode sputtering. Changes in the foil shape are related to current distribution along the hollow cathode axis. The experimental results aid in understanding the increase in spectral lines intensities emitted from conical bottom hollow cathode lamps.

Optical rotary connector

As optical fiber usage widens, a new kind of optical fiber connector becomes necessary. This connector would be connecting two optical fiber bundles with different speeds around an axis without interruption. It is difficult to make such a connector, especially one with a hollow axis used for mechanical power transmissions. Using an optical fiber bundle for an image inversion and a differential gear system, we have developed an optical rotary connector with a hollow axis that can be used for a multichannel connection.