Positions Of Column Research Articles

Fast-nondestructive measurement of axial slice water content and water distribution with NMR SFG-MSCPMG sequence

Measuring hydraulic conductivity by instantaneous profile method needs to detect the pore water content of soil at different positions, but most of the detecting methods will disturb the soil sample. In the study, the axial slice scanning of soil samples was carried out by using static filed gradient multi-slice Carr-Purcell-Meiboom-Gill (SFG-MSCPMG) sequence of nuclear magnetic resonance (NMR) technology, which can nondestructively determine water content and distribution at different positions of soil column. In this experiment, three clays were used to illustrate the relationship between NMR test results and oven drying results of water content. The results show that there is a good linear relationship between the NMR signal and water content. Combining mercury intrusion porosimetry (MIP) data, the transverse surface relaxivity parameters (ρ2) of clays are obtained. With ρ2 = 41.90 μm/s the T2 distribution curve of pore water in the ordinary clay can be converted into the pore water distribution curve, which is in good agreement with that obtained with MIP. Nevertheless, it is found that the T2 distribution curve of pore water in expansive clay obtained with NMR technique is more suitable for analyzing the average pore water distribution because of the fast exchange of pore water between the interlayers, intra-aggregates and inter-aggregates in expansive clay.

Correlation Research between Asymmetry Coefficient of Gondola Car Body and Stress Distribution of Cross Bearer Weld

In order to find out the root cause of cross bearer welds’ cracks in general-purpose gondola cars, the relationship between asymmetric structure and stress distribution is studied in this paper. Firstly, the concept of asymmetry coefficient and stress distribution cluster is proposed, and the asymmetric coefficients’ calculation methods of independent and dependent variables are given, respectively, in two-dimensional space. Secondly, according to the different positions of side column 1 and side column 2, 30 local models are established, the cross bearer weld stresses are extracted after finite element simulation, and the stress distribution clusters of cross bearer weld stresses are formed. Finally, the asymmetry coefficients of the side columns are calculated, and the correlation between the positions of the side columns and the weld stresses is studied using the methods of Pearson correlation coefficient and complex correlation coefficient. The results show that the correlation between the stress of cross bearer weld 2 and the positions of the side columns is much higher than that between the stress of cross bearer weld 1 and the positions of the side columns. Meanwhile, it shows that the method presented in this paper is feasible and effective for the analysis and research of asymmetric structures. These combined with the calculation method of the correlation coefficient.

Influence of surfactant on the permeability at different positions of a leaching column.

To solve the problems of poor permeability and low leaching rate in ore heap leaching, solid surface physical chemistry, seepage mechanics theory for porous media, CT scanning and SEM were used to carry out column leaching tests with a homemade segmented removable plexiglass column; the variation law for the permeability coefficients of each segment of the leaching column before and after leaching was analyzed. The experimental results showed that there was little difference in the permeability coefficient of ore at different heights before leaching. After leaching, the permeability coefficients were unevenly distributed along the column height, and the lowest value was located at the bottom of the leaching column. The addition of surfactant provided an obvious improvement in the permeability of the leaching column. The permeability coefficient at the bottom of the leaching column was 6% higher than that of the control group. At the same time, the addition of surfactant increased the leaching rate of ore by nearly 10%. A theoretical analysis showed that the surfactant improved the permeability of ore heaps mainly by preventing physical blockage by fine particles and inhibiting deposition of chemical products.

Dynamics of functional changes in the spinal column in scoliosis in children in the use of adaptive physical activity techniques

Objective . To evaluate the effectiveness of spinal correction in scoliosis in children in the process of adaptive physical activity (APA). Materials and methods . A study conducted at the Republican Research Center for Radiation Medicine and Human Ecology involved 60 children with scoliosis of varying severity. A course of spinal correction by APA means, forms, and techniques was performed. Results . The conducted study on the use of the scoliosis correction course has showed the effectiveness of the applied means and techniques. It has been proved that children undergoing the developed course in contrast to children undergoing the generally accepted course, reveal a significant improvement in almost all indicators of the positions of the spinal column, namely: lateral deviation of the spine axis (p=0.028), thoracic kyphosis (p<0.001), pelvic tilt (p=0.049), rotation of the left superficial plane (p=0.045). At the trend level, an improvement in the following indicators was noted: lumbar lordosis (p=0.086), rotation of the right superficial plane (p=0.064), lateral deviation to the right (p=0.096). Conclusion . It has been proved that the performed spinal correction course in children with scoliosis in the process of APA is effective.

Effect of the Wave on Sediment Suspension and the Morphological Pattern of Ripple Formation

The paper presents the evolution of the morphological structures of a fine sand bed subjected to a turbulent flow field associated with the propagation of unidirectional surface waves. In particular, starting from a flatbed, the instability of the sediment grains from the ripple formation initiation state to the quasi-equilibrium state was observed in a wave flume. During the rolling grain ripple formation stages, new ripples appeared at each trough due to the doubling transition phenomenon and the ripples migrated soon after their formation. Observations showed that the wavelength of the bed forms that appeared during the rolling grain stage was about half of that observed at the quasi-equilibrium stage. Further, the suspended sediment concentration above the ripple bed varied with the number of wave cycles and at different vertical positions of the water column—as evidenced from the present experiments. The power spectral density of the turbulent velocity fluctuations showed that the transition of the rolling grain to vortex ripples occurred between 400 and 500 cycles with signatures of distinct reduction of near-bed spectral energy at the quasi-equilibrium state. It is evident from the stress ellipsoid that until the transition from rolling grain ripples to vortex ripples occurred, the ejection and the sweeping turbulent bursting structures took the leading role in the transportation of sediment. Thereafter, gradually the outward- and inward-interacting turbulent bursting structures provided the major contribution to the Reynolds shear stresses during the different evolution stages of vortex ripples and also at the quasi-equilibrium stage.

Analyses of deuterium retention in tungsten and graphite first wall materials by laser-induced ablation spectroscopy on EAST

• Combined LIBS and LIAS measurements were applied to determine the dynamic deuterium retention in C and W during EAST discharges. • LIAS measurements show more than three times higher deuterium retention in graphite than in tungsten during EAST discharges. • The deuterium retention on the graphite PFC is saturated within 0.2 s plasma exposure for limited magnetic configuration when the plasma actively touches the first wall. • The deuterium retention in the start-up phase is significantly larger than during the discharge for diverted magnetic configuration. Plasma-wall interactions at the first wall in fusion experimental devices are critical for the life time of plasma-facing components and tokamak operation. In-situ measurements of these plasma-wall interaction processes are required in long pulse devices in order to understand better the underlying mechanisms as well as monitoring of the tritium content of the first wall as an immediate safety application. In this work we present measurements of the deuterium retention in the first wall of EAST using laser-induced ablation spectroscopy. The diagnostic is applied during plasma operation and the dynamic retention for graphite and tungsten as plasma-facing materials are compared, showing more than three times higher short-term retention in graphite than in tungsten. Laser-based analysis is applied during a shift of the vertical positions of the plasma column in limited as well as in the start-up phase of discharges in diverted magnetic configuration. Plasma core densities of n e = (1.5–3.2) × 10 19 /m 3 are chosen to vary the ion flux to the first wall and study saturation effects of deuterium on the surface first wall materials during tokamak plasma operation. A linear dependence of the retention from ion fluence is observed for graphite as PFC up to 3 × 10 18 D + /cm 2 , followed by a constant retention up to fluences of 3.5 × 10 19 D + /cm 2 for nearby first wall temperatures of T PFC ≈ 350 K.

Separation of methanol-chloroform mixture using pressure-swing distillation: Modeling and optimization

The separation of methanol-chloroform mixture, a minimum-boiling azeotrope, is performed using pressure- swing distillation process via process simulation. In this study, the steady-state optimization was carried out using PRO/II with PROVISION v.10. The two different column configurations (low-to-high pressure and high-to-low pressure) were compared wherein the positions of the low-pressure column and high-pressure column were operated interchangeably to attain an optimized design. Additionally, different heat-integration configurations (partial heat- and full heat-integration) were applied to lessen the overall utility consumption. It was determined that the low-to-high pressure column configuration provided a more optimized result for all heat-integrated systems as compared to high-tolow pressure column configuration. Application of heat-integration further decreases the cooling water and steam consumption by 38.86% and 35.74%, respectively, for partial heat-integrated system, and by 44.58% and 41.01%, respectively, for full heat-integrated system.

Analysis of Gaze Fixation at the Heading Positions of Column Shown in the Table of Life Science Textbooks

Analysis of Gaze Fixation at the Heading Positions of Column Shown in the Table of Life Science Textbooks

Measurements of Absolute Atomic Nitrogen Density by Two-Photon Absorption Laser-Induced Fluorescence Spectroscopy in Hot Air Plasma Generated by Microwave Resonant Cavity

For the first time, absolute densities of atomic nitrogen in its ground state (N4S) have been measured in hot dry and humid air plasma columns under post-discharge regime. The determination of space-resolved absolute densities leads to obtain the dissociation degrees of molecular nitrogen in the plasma. The hot plasmas are generated inside an upstream gas-conditioning cell at 600 mbar when the air gas flow is directly injected at 10 slm in a microwave resonant cavity (2.45 GHz, 1 kW) placed in the downstream side. Density measurements based on laser induced fluorescence spectroscopy with two-photon excitation (TALIF), are more particularly performed along the radial and axial positions of the plasma column. Calibration of TALIF signals is performed in situ (i.e. in the same gas-conditioning cell but without plasma) using an air gas mixture containing krypton. Optical emission spectroscopy is considered to estimate the rotational gas temperature by adding a small amount of H2 in dry air to better detect OH (A-X) spectra. The rotational temperatures in humid air plasma column (50% of humidity) are larger than those of dry air plasma column by practically 30% near the nozzle of resonant cavity on the axis of the plasma column. This is partly due to attachment heating processes initiated by water vapor. A maximum of the measured absolute nitrogen density is also observed near the nozzle which is also larger for humid air plasma column. The obtained dissociation degrees of molecular nitrogen in both dry and humid air plasma along the air plasma column are lower than the cases where only thermodynamic equilibrium is assumed. This is characteristic of the absence of chemical and energetic equilibria not yet reached in the air plasma column dominated by recombination processes.

Experimental Observation of Bohr's Nonlinear Fluidic Surface Oscillation.

Niels Bohr in the early stage of his career developed a nonlinear theory of fluidic surface oscillation in order to study surface tension of liquids. His theory includes the nonlinear interaction between multipolar surface oscillation modes, surpassing the linear theory of Rayleigh and Lamb. It predicts a specific normalized magnitude of 0.416η2 for an octapolar component, nonlinearly induced by a quadrupolar one with a magnitude of η much less than unity. No experimental confirmation on this prediction has been reported. Nonetheless, accurate determination of multipolar components is important as in optical fiber spinning, film blowing and recently in optofluidic microcavities for ray and wave chaos studies and photonics applications. Here, we report experimental verification of his theory. By using optical forward diffraction, we measured the cross-sectional boundary profiles at extreme positions of a surface-oscillating liquid column ejected from a deformed microscopic orifice. We obtained a coefficient of 0.42 ± 0.08 consistently under various experimental conditions. We also measured the resonance mode spectrum of a two-dimensional cavity formed by the cross-sectional segment of the liquid jet. The observed spectra agree well with wave calculations assuming a coefficient of 0.414 ± 0.011. Our measurements establish the first experimental observation of Bohr’s hydrodynamic theory.

Measurement and analysis of truck vibration levels as a function of packages locations in truck bed and suspension

During transport, due to vibration fruits and vegetables could be damaged. The vibration levels that transfer to fruits and vegetables may depend not only on vehicle characteristics (speed and suspension) and the road characteristics but also on the position of boxes packed in truck bed. The purpose of this research was to determine and analyze the vibration that occurs during truck transport as a function of box position and fruit position within the truck bed. For this purpose, two commercial trucks were used (with leaf-spring suspension and air-ride suspension). Test controllable factors includes: height positions of the container column (Bottom, Middle and Up), position of the container along the truck-bed (front axle and rear axle) and depth of fruit inside the container (Down and Top). The obtained values of the power spectral density were used to survey the effect of container positions on fruit vibration. RMS values were also obtained for different positions. The results showed that the power spectral density (PSD) was dependent on the position along the floor of the trucks. Higher vibration levels were recorded for fruits on top of the column. As the fruit height within a box increased, the vibration levels increased. ANOVA test results indicated that the considered factors significantly affected PSD values (Average PSD in the range of 0.1–5Hz and peak PSD) and root mean square of acceleration (P<0.05).

Investigation on the characteristics of dielectric barrier discharge with fairly large volume generated in air at atmospheric pressure

By using a tri-electrode dielectric barrier discharge device, a uniform discharge with fairly large volume is realized in the main discharge region in atmospheric pressure air. The characteristics of the main discharge are investigated by optical and electrical methods. Results show that the main discharge includes two discharge modes with changing the input power of the source, which are a plasma plume discharge and a plasma column discharge. The inception voltage decreases with the increase of the peak value of the applied voltage for plume discharge. It can be deduced that the pre-ionization of air in the main discharge region is important for the main discharge, which results from the UV emitted from the coaxial dielectric barrier discharge. Spatially resolved measurements are conducted on the plasma plume and the plasma column with photomultiplier tubes. It is found that the plasma plume behaves like a plasma bullet that corresponds to a fast moving layer of light emission zone. Comparatively, the discharges at different positions of the plasma column almost volley, which means that the plasma column is of continuous discharge. Through analyzing the optical spectrum emitted from the main discharge, the vibrational temperature and rotational temperature are calculated. Results indicate that both the vibrational temperature and the rotational temperature decrease with the increase of peak value of the applied voltage. These results are of significance for the industrial applications of dielectric barrier discharge.

Radial and Vertical Displacement Events of Plasma in the Damavand Tokamak

The plasma current in tokamak is under the influence of forces in such a way it tents toward the radial expansion. The forces resulting from external self-induced, internal inductance, thermal energy, and magnetic field fluctuations on the plasma column, cause radial expansion. To keep plasma in its position, the Lorentz force should be applied by vertical magnetic field to balance these forces. Control of the plasma position in the radial direction is very complicated. Poloidal beta, βθ, and the internal inductance parameter depend on plasma current where plasma current parameters themselves are not steady in tokamak. The experimental data of Damavand tokamak is used to compare radial displacement with theoretical prediction. Temporal variation of plasma current along with time variation of R and Z positions of the plasma column is studied. The vertical displacement event takes place because of the elongated cross section of plasma column. Theoretical and experimental results show reasonable agreement.

Fascicle switching generates a chiasmal neuroarchitecture in the embryonic central body of the grasshopper Schistocerca gregaria

The central body is a prominent neuropilar structure in the midbrain of the grasshopper and is characterized by a fan-shaped array of fiber columns, which are part of a chiasmal system linking anterior and posterior commissures. These columns are established during embryogenesis and comprise axons from cell clusters in the pars intercerebralis, which project to the central body via the so-called w, x, y, z tracts. Up to mid-embryogenesis the primary axon scaffold in both the brain and ventral nerve cord comprises a simple orthogonal arrangement of commissural and longitudinal fiber pathways. No chiasmata are present and this pattern is maintained during subsequent development of the ventral nerve cord. In the midbrain, individual axons entering the commissural system from each of the w, x, y, z tracts after mid-embryogenesis (55%) are seen to systematically de-fasciculate from an anterior commissure and re-fasciculate with another more posterior commissure en route across the midline, a feature we call “fascicle switching”. Since the w, x, y, z tracts are bilaterally symmetrical, fascicle switching generates chiasmata at stereotypic locations across the midbrain. Choice points for leaving and entering fascicles mark the anterior and posterior positions of each future column. As the midbrain neuropil expands, the anterior and posterior groups of commissures condense, so that the chiasmata spanning the widening gap between them become progressively more orthogonally oriented. A columnar neuroarchitecture resembling that of the adult central body is already apparent at 70% of embryogenesis.

Electron density measurements from right-hand cutoff of ECE in the TCABR tokamak

In tokamak machines with low toroidal magnetic fields and high plasma densities, the accessibility conditions impose restrictions to the detection of the Electron Cyclotron Emission (ECE). In these machines, the righthand cutoff condition can be used as an independent method to determine the local electron density from the ECE data in thermal discharges. In this paper is shown the results obatined from the detection of ECE radiation in the TCABR tokamak, in operation at the Institute of Physics of University of São Paulo. The effect of the ECE radiation cutoff was observed for different radial positions of the plasma column. To reach the ECE cutoff condition, the electron density was increased monotonically by the use of an external gas puffing system. For sufficient high densities, the emission at some frequencies is cutoff and the first and the last frequency to be cutoff depends on the shape of the density profile. These measurements do not require the plasma to be optically thick. It was observed that, for a toroidal field B O = 1:14T, the first cutoff of ECE occurs for a radial position r <FONT FACE=Symbol>@</FONT> 5 cm. From these measurements the radial electron density was determined. For a symmetric parabolic profile n e = n eo [1 - (r/a)²]alpha , values of alpha between 0.86 and 0.97 were experimentally obtained. A good agreement of these values with those obtained from the microwave interferometer measurements (<FONT FACE=Symbol>a »</FONT>0:85) was found. Therefore, the ECE right-hand cutoff constitutes an independent method to obtain information about the electron density profile.

Formation of electrostatic double-layers and electron-holes in a low pressure mercury plasma column

Experimental studies of the formation of electrostatic double layers (DLs) and electron-holes (e-holes) are reported. The measurements were performed in the positive column of a mercury arc discharge operating in the low-pressure range of (2.0–14.0) × 10−2 Pa with current density in the range of (3.0–8.0) × 103 A m−2. Stable and unstable modes of the discharge were identified as the current was gradually increased, keeping constant the vapour pressure. The discharge remains stable until a critical current from which a slight increase of the current leads to an unstable regime characterized by high discharge impedance and strong oscillations. This mode ceased after a DL was formed in the plasma column. To induce the DL formation and to transport it smoothly along the discharge column, a low intensity B-field (7–10) × 10−3 T produced by a movable single coil was used. The B-field locally increases the electron current density and makes the DL form at the centre of the magnetic constriction where it remained at rest. Electrostatic potential structures compatible with ordinary DLs and multiple-layers could be formed in the plasma column by dealing with the combined effects of the operational parameters of the discharge. It is noticeable that a pure e-hole, which is a symmetric triple-layer having a bell shape potential profile, could easily be formed by means of this experimental technique. A partial kinetic description, based on the space charge structure derived from an experimental e-hole, is presented in order to infer the charged particle populations that could contribute to the space charge of the e-hole. Evidence is shown that strong e-hole formation might be driven by an ion beam, therefore it could not be formed in isolation since its formation requires a nearby ion accelerating potential structure. Probe measurements of the plasma properties, at various radial positions of the stable positive column, are also presented. In the stable mode, prior to current limitation, the probe data reveal a substantial radial decrease of the electron drift velocity. This result calls for a review of the free fall theories of low pressure plasma columns to take into account this non-uniformity of the electron drift velocity.

Study of uniformity of plasmas produced in a wall‐stabilized arc

AbstractIn this contribution the plasma of an arc discharge in a mixture of helium and argon is studied. The gas mixture is introduced uniformly along the arc column between each of the stabilizing plates. From the measured lateral distribution of radiation (HeI, HI, ArI, ArII, NI, FI line intensity and width measurements), after Abel inversion, the radial temperature distributions were obtained at various positions of the arc column. Beside the expected radial temperature gradients, a distinct temperature gradient along the arc column was found.

Surface wave transition before breakup on a laminar liquid jet

Problems of liquid jet breakup are very fundamental in the fluid-dynamics and application fields of atomization. Instability theories of the surface wave were usually used to describe the breakup phenomena. In these theories, it was assumed that the surface wave was a regular sinusoidal wave. However, irregular surface waves were frequently observed even though a liquid jet was laminar. In this paper, the surface wave structure on a vertically injected laminar liquid jet was experimentally investigated. The amplitude of the surface wave was detected by a photo-sensor system and its frequency spectrum was derived by an FFT analyzer. In the spectrum, there were many discrete peaks which were not in harmonic relation with each other. Further, a broad band spectrum appeared near the breakup point. These results indicated that the surface wave consisted of several waves with various modes. The breakup phenomena included the irregular motions even in a laminar liquid jet. Cross-correlation between two waves at different positions of the liquid column was derived. Since the similarity between two waves was evaluated by the cross-correlation function, the surface wave transition along the flow direction could be obtained. When the surface wave grew up to the large amplitude wave near the breakup point, it changed rapidly from regular to irregular wave.

Relative Positions of the Thermal Convection Column and Smoke Plume Generated from a Smoldering Cigarette

Abstract The relative positions of the thermal convection column and the smoke plume from a variety of smoldering cigarettes were measured using a combination of schlieren and visual optical systems. The schlieren technique is an optical method used to observe refractive index gradients in gases and other clear media. The refractive index gradients can be caused by variations in pressure, composition or temperature. The convection column of heated air and combustion gases rising from a cigarette coal was observed with a two mirror schlieren system. A video camera was used as the observing device rather than the usual photographic camera. A second video camera was arranged to view the smoke plume rising from the coal region. The two video images were combined with a video special effects generator and were viewed on a single monitor. The behaviour and relative positions of both columns were thus observed in real time with two non-invasive optical methods. The schlieren images of the convection column were compared to those of model systems such as a heated cylinder and a small flame. Results for experimental cigarettes with paper porosities of 12 cm/min to 48 cm/min (Coresta) during smolder showed that the thermal convection column was centered 2 mm to 3 mm in front of the paper char line directly over the hottest part of the coal as determined by infra-red imaging. The smoke plume was centered 2 mm behind the paper char line and the position did not change with paper porosity. Results for experimental cigarettes made with a commercially available low sidestream paper showed that the position of the convection column did not change. However, the position of the smoke plume changed considerably. In addition to being markedly decreased in visibility, the plume now appeared to be centered directly over the paper char line. This change in position provides a valuable insight into the mechanism of smoke reduction. The low sidestream papers seem to work by preventing the escape of smoke forming condensibles through the paper behind the paper char line. The condensibles are therefore forced to escape at the paper char line and undergo increased combustion and pyrolysis. As a result, some are converted to lower molecular weight materials and are unable to condense as readily to form the smoke. In addition, the remaining condensibles are released into a hotter and faster rising gas stream. This serves to reduce smoke formation by suppressing condensation and increasing dilution.

A long-lived thymidine pool in epithelial stem cells.

The labelling index (LI) of the individual basal cell positions of the anterior column of mouse tongue filiform papillae was assessed with time after an injection of [3H]TdR at 12.00 hours (the minimum point in the circadian LI rhythm). An initial doubling of the LI in the stem cell zone due to cell division was followed by a second rise of 14-16% 16 hr after injection and this occurred even in the presence of vincristine. Although the uptake of [3H]TdR and the initial LI doubling were largely prevented by a preceding injection of hydroxyurea, the 14-16% LI rise was still observed. The possible explanations are discussed, the favoured one being that an average of one of the six or seven cells (the stem cell) in each stem cell zone can store [3H]TdR in a long-lived precursor pool for at least 16 hr before being utilized for DNA synthesis. This complements previously published work which suggested that one cell in each stem cell zone may selectively segregate DNA at mitosis.