Horizontal Coil Research Articles

Depreissia decipiens, an enigmatic canopy spider from Borneo revisited (Araneae, Salticidae), with remarks on the distribution and diversity of canopy spiders in Sabah, Borneo.

Depreissia is a little known genus comprising two hymenopteran-mimicking species, one found in Central Africa and one in the north of Borneo. The male of Depreissia decipiens is redescribed, the female is described for the first time. The carapace is elongated, dorsally flattened and rhombus-shaped, the rear of the thorax laterally depressed and transformed, with a pair of deep pits; the pedicel is almost as long as the abdomen. The male palp is unusual, characterized by the transverse deeply split membranous tegulum separating a ventral part which bears a sclerotized tegular apophysis and a large dagger-like retrodirected median apophysis. The female epigyne consists of one pair of large adjacent spermathecae and very long copulatory ducts arising posteriorly and rising laterally alongside the spermathecae continuing in several vertical and horizontal coils over the anterior surface. Relationships within the Salticidae are discussed and an affinity with the Cocalodinae is suggested. Arguments are provided for a hypothesis that Depreissia decipiens is not ant-mimicking as was previously believed, but is a mimic of polistinine wasps. The species was found in the canopy in the Kinabalu area only, in primary and old secondary rainforest at 200–700 m.a.s.l. Overlap of canopy-dwelling spider species with those in the understorey are discussed and examples of species richness and endemism in the canopy are highlighted. Canopy fogging is a very efficient method of collecting for most arthropods. The canopy fauna adds an extra dimension to the known biodiversity of the tropical rainforest. In southeast Asia, canopy research has been neglected, inhibiting evaluation of comparative results of this canopy project with that from other regions. More use of fogging as a collecting method would greatly improve insight into the actual species richness and species distribution in general.

立体形状の熱可塑性CFRPの損傷修復および非破壊検査技術に関する研究

In recent years, there is a demand for repair of damage of thermoplastic CFRP (CFRTP) of three dimensional shape and its non-destructive inspection techniques for the securement of soundness. This study aims to establish repairing damage and non-destructive testing method that can be applied to the CFRTP of the three dimensional shape by developing conventional studies of non-destructive inspection method using an electromagnetic phenomenon. First, we analyzed the eddy current density and the heat rate of CFRTP by proposed rectangular coil using the finite element method software (COMSOL Multiphysics 5.2). Second, we investigated the temperature characteristics of CFRTP using the proposed rectangular coil. As a result, we confirmed that vertical rectangular coil is possible to detect local defect of CFRTP and melt CFRTP as compared with the horizontal rectangular coil. In addition, the vertical rectangular coil sufficiently heated CFRTP under winding wire of the coil and melted surface of CFRTP as compared with the horizontal rectangular coil.

A Case of Wide Necked Basilar Tip Aneurysm Treated with Horizontal Stent-assisted Coil Embolization

A Case of Wide Necked Basilar Tip Aneurysm Treated with Horizontal Stent-assisted Coil Embolization

Effect of Coil Torsion on Heat Transfer and Pressure Drop Characteristics of Shell and Coil Heat Exchanger

The present work introduces an experimental study of horizontal shell and coil heat exchangers. Characteristics of the convective heat transfer in this type of heat exchangers and the friction factor for fully developed flow through their helically coiled tube (HCT) were investigated. The majority of previous studies were performed on HCTs with isothermal and isoflux boundary conditions or shell and coil heat exchangers with small ranges of HCT configurations and fluid-operating conditions. Here, five heat exchangers of counterflow configuration were constructed with different HCT torsions (λ) and tested at different mass flow rates and inlet temperatures of both sides of the heat exchangers. In total, 295 test runs were performed from which the HCT-side and shell-side heat transfer coefficients were calculated. Results showed that the average Nusselt numbers of both sides of the heat exchangers and the overall heat transfer coefficient increase by decreasing coil torsion. At lower and higher HCT-side Reynolds number (Ret), the average increase in the HCT-side average Nusselt number (Nu¯t) is of 108.7% and 58.6%, respectively, when λ decreases from 0.1348 to 0.0442. While, at lower and higher shell-side Reynolds number (Resh), the average increase in the shell-side average Nusselt number (Nu¯sh) is of 173.9% and 69.5%, respectively, when λ decreases from 0.1348 to 0.0442. In addition, a slight increase of 6.4% is obtained in the HCT Fanning friction factor (fc) at lower Ret when λ decreases from 0.1348 to 0.0442, and this effect vanishes with increasing Ret. Furthermore, correlations for Nu¯t, Nu¯sh, and fc are obtained.

Determining soil salinity and plant biomass response for a farmed coastal cropland using the electromagnetic induction method

Apparent electrical conductivity (ECa) measured by electromagnetic induction (EM) instruments has been successfully used as an ancillary variable to estimate soil salinity from field to watershed scales. It is particularly useful in the case of coastal farming area where reliable estimates of soil salinity aid farmers and researchers in understanding the development of salinization and establishing appropriate management practices. The objectives of this research were to estimate soil salinity (ECe) using intensive EM survey data and prediction equations relating soil salinity to ECa, to determine the optimal data interval in EM survey and to validate the prediction reliability using plant biomass response to soil salinity. This study was conducted in a typical coastal rain-fed farmland in north Jiangsu Province, China. The results indicated that apparent electrical conductivity showed significant correlation with ECe and EM readings from the horizontal coil orientation can be used as the sole predictor in a linear mixed model. Field EM survey data exhibited directional trend resulting from the impact of anthropogenic activities on soil salinity. An optimal sampling interval of 16m in the survey transect essentially meets the need of spatial prediction when field EM survey is performed. Soil salinity increased with depth and higher soil salinity mainly occurs in areas where rice was previously planted, particularly in lower-lying regions and areas adjacent to the aquaculture plant. Plant biomass is negatively related to both, measured and estimated soil salinity. The relation to measured soil salinity was closer than to estimated soil salinity. Boundary line analysis shows that root zone salinity (ECe) causes a 4.4% and 6.4% plant biomass reduction per dS/m for rice and cotton, respectively. Such results allowed us to conclude that a larger data interval of EM survey than the present could produce satisfactory estimation accuracy of field soil salinity, and the relationship between soil salinity (or ECa data) and plant biomass could help to derive site specific yield goals and management practices in the farmed coastal cropland.

Effect of γ-Al2O3/Water Nanofluid on Heat Transfer and Pressure Drop Characteristics of Shell and Coil Heat Exchanger With Different Coil Curvatures

This study presents an experimental investigation of the characteristics of convective heat transfer in horizontal shell and coil heat exchangers in addition to the friction factor for fully developed flow through their helically coiled tube (HCT). Five heat exchangers of counterflow configuration were constructed with different HCT-curvature ratios (δ) and tested at different mass flow rates and inlet temperatures of γ-Al2O3/water nanofluid in the HCT. The tests were performed for γ-Al2O3 with average size of 40 nm and particles volume concentration (ϕ) from 0% to 2% for 0.0392≤δ≤0.1194. Totally, 750 test runs were performed from which the HCT-average Nusselt number (Nu¯t) and fanning friction factor (fc) were calculated. Results illustrated that Nu¯t and fc of nanofluids are higher than those of the pure water at same flow condition, and this increase goes up with the increase in ϕ. When ϕ increases from 0% to 2%, the average increase in Nu¯t is of 59.4–81% at lower and higher HCT-Reynolds number, respectively, and the average increase in fc is of 25.7% and 27.4% at lower and higher HCT-Reynolds number, respectively, when ϕ increases from 0% to 2% for δ=0.1194. In addition, results showed that Nu¯t and fc increase by increasing coil curvature ratio. When δ increases from 0.0392 to 0.1194 for ϕ=2%, the average increase in Nu¯t is of 130.2% and 87.2% at lower and higher HCT-Reynolds number, respectively, and a significant increase of 18.2–7.5% is obtained in the HCT-fanning friction factor at lower and higher HCT-Reynolds number, respectively. Correlations for Nu¯t and fc as a function of the investigated parameters are obtained.

Enhanced heat and mass transfer in alternating structure of tubes and longitudinal trough mesh packing in lithium bromide solution absorber

For enhancing the vapour absorption in LiBr solution systems, a novel absorber with tube and mesh packing alternating structure is designed and investigated. Stainless steel mesh screens are folded as the longitudinal trough mesh packing, and inserted to the gaps of horizontal tubes to make the absorbent flow through the tube and mesh packing regimes successively, thus forming an alternating heat and mass transfer absorption process. Experimental investigation is conducted to characterize the absorption performance of the absorption bodies of this alternating structure and conventional horizontal coils. The results show that the average mass transfer rate and cooling load are increased by 17.2% and 6.23% respectively, which confirms that the alternating structures can promote the absorption. The mesh packing provides extended absorption area, slows down the flow and well mingles the solution, which are all beneficial for vapour absorption.

Experimental Investigation of Coil Curvature Effect on Heat Transfer and Pressure Drop Characteristics of Shell and Coil Heat Exchanger

The present work experimentally investigates the characteristics of convective heat transfer in horizontal shell and coil heat exchangers in addition to friction factor for fully developed flow through the helically coiled tube (HCT). The majority of previous studies were performed on HCTs with isothermal and isoflux boundary conditions or shell and coil heat exchangers with small ranges of HCT configurations and fluid operating conditions. Here, five heat exchangers of counter-flow configuration were constructed with different HCT-curvature ratios (δ) and tested at different mass flow rates and inlet temperatures of the two sides of the heat exchangers. Totally, 295 test runs were performed from which the HCT-side and shell-side heat transfer coefficients were calculated. Results showed that the average Nusselt numbers of the two sides of the heat exchangers and the overall heat transfer coefficients increased by increasing coil curvature ratio. The average increase in the average Nusselt number is of 160.3–80.6% for the HCT side and of 224.3–92.6% for the shell side when δ increases from 0.0392 to 0.1194 within the investigated ranges of different parameters. Also, for the same flow rate in both heat exchanger sides, the effect of coil pitch and number of turns with the same coil torsion and tube length is remarkable on shell average Nusselt number while it is insignificant on HCT-average Nusselt number. In addition, a significant increase of 33.2–7.7% is obtained in the HCT-Fanning friction factor (fc) when δ increases from 0.0392 to 0.1194. Correlations for the average Nusselt numbers for both heat exchanger sides and the HCT Fanning friction factor as a function of the investigated parameters are obtained.

Eddy-Current Coil Interaction With A Perfectly Conducting Wedge of Arbitrary Angle

In this article, a closed-form expression for the impedance of a tangential eddy-current coil in the presence of an infinite conducting wedge of arbitrary angle is derived. The truncated eigenfunction expansion (TREE) solution given here is valid in the quasi-static frequency regime. The theory was validated via comparison to an independent analytical expression for the impedance change of a horizontal coil over a conducting half-space due to Burke. We present results for three geometries: a conducting quarter-space, a conducting wedge of angle 225 degrees, and a semi-infinite conducting sheet. Our theory predicts a measurable change in the tangent coil reactance in the presence of all three geometries.

Analytical compensation of axisymmetric equilibrium fluxes picked up by locked mode detectors in tokamaks.

In the detection of locked modes using saddle loops, the problem of how to remove the axisymmetric equilibrium flux picked up by the loops has still to be solved. The problem becomes more difficult when there are conductive structures located near the saddle loops. In this paper, we present an analytical model based on lumped eddy current circuits and use it to interpret the measured equilibrium flux and the corresponding eddy current fluxes. Using this model, precise compensation for fluxes induced by the horizontal field coils and the toroidal field coils, with relative errors of less than 1%, has been realized for the saddle loops in the Joint Texas Experimental Tokamak. This paper also presents a new method to compensate for the detection of equilibrium flux by the locked mode detector.

Condensation of R-134a inside a helically coiled tube-in-shell heat exchanger

This article presents an experimental investigation of heat transfer and pressure drop characteristics of R-134a condensing inside a horizontal helical coil tube with the cooling water flowing in the shell in counter flow direction. The test runs are performed at vapor saturation temperature 35±0.5 and 40±0.5°C for the mass flux varying from 100 to 350kgm−2s−1 and vapor quality ranging from 0.1 to 0.9. The flow regimes observed during the experiment have been plotted on Taitel and Dukler and mass flux versus vapor quality flow map. The transitions between different flow regimes have also been discussed. The effect of mass flux, vapor quality and saturation temperature on the heat transfer coefficient and pressure drop have been investigated. The experimental results of the helical coil tube are compared to straight tube. The thermodynamic advantage of helical coil over straight tube is evaluated in terms of enhancement parameter. The enhancement parameter is higher than one for mass fluxes lower than 200kgm−2s−1. The correlations have been developed to predict two-phase Nusselt number and frictional pressure drop multiplier during condensation of R-134a inside horizontal helical coil tube.

An Experimental Study on Performance During Reverse Cycle Defrosting of an Air Source Heat Pump with a Horizontal Three-circuit Outdoor Coil

When the surface temperature of the outdoor coil in an air source heat pump (ASHP) unit is below both the air dew point and freezing point of water, frost can be formed and accumulated over the surface of the outdoor coil, which is usually of multi-circuit structure in order to minimize its refrigerant pressure loss and enhance the heat transfer between refrigerant and ambient air. However, frosting adversely affects the operational performance and hence the energy efficiency of the ASHP unit, therefore periodic defrosting is necessary. Currently, the most widely standard defrosting method used for ASHP units is reverse cycle defrosting. A previous related study has suggested that during reverse cycle defrosting, downwards flowing of melted frost due to gravity over a vertical multi-circuit outdoor coil in an ASHP unit could deteriorate defrosting performance, by using more energy for defrosting and prolonging a defrosting process. If however an outdoor coil can be horizontally installed, the flow path for melted frost over coil surface can be shortened, and a better defrosting performance expected. In this paper, therefore, an experimental study on performance during reverse cycle defrosting of an ASHP unit having a horizontal three-circuit outdoor coil has been carried out. Firstly, a detailed description of the ASHP unit is presented. This is followed by reporting the experimental results. Finally, a comparative and quantitative analysis is given.

Error Analysis in Measured Conductivity under Low Induction Number Approximation for Electromagnetic Methods

We present an analysis of the error involved in the so-called low induction number approximation in the electromagnetic methods. In particular, we focus on the EM34 equipment settings and field configurations, widely used for geophysical prospecting of laterally electrical conductivity anomalies and shallow targets. We show the theoretical error for the conductivity in both vertical and horizontal dipole coil configurations within the low induction number regime and up to the maximum measuring limit of the equipment. A linear relationship may be adjusted until slightly beyond the point where the conductivity limit for low induction number (B=1) is reached. The equations for the linear fit of the relative error in the low induction number regime are also given.

136. Magnetic stimulation of the cervical spine: Effect of coil current configuration on the MEPs

Magnetic stimulation over the spine is san available method to stimulate proximal nerve axon: the probable site of excitation is considered very close to exit of cervical roots. It is argued that the spatial derivative of induced electric field parallel to the nerve axon is crucial factor to elicit nerve action potential. We study the effect of coil current configuration in magnetic stimulation of cervical roots on MEPs, assuming that the direction of coil current occurring at the intersection of figure eight coil (transverse vs perpendicular to the nerve) might be related to oriented axons. Five healthy subjects were stimulated by eight shaped coil placed over the cervical spine between C5 and T2 spine processes; the coil direction was orthogonally changed (vertical vs horizontal) along the midline (cervical spine) and along parallel lines (1, 2, 3 cm outer on right and left side). The amplitude of MEPs are significantly higher by using vertical vs horizontal coil position at any site of stimulation and results are referred to the former experimental trial. MEP amplitude at 60% output: the mean maximum amplitude was along C7 line at position +2 cm, both on the right (4,4 mV) and left (4,6 mV) side. MEP amplitude at 70% output: the mean maximum amplitude was along C7 line at position +2 cm, both on the right (8,82 mV) and left (7,96 mV) side. MEP amplitude along T1 line was slightly lower than at C7 level, without significant difference. Magnetic stimulation using commercially available device is easy to perform, but the MEP characteristics must be rigorously used to couple anatomy with physical properties of the stimulus enough to improve the clinical relevance of this method and the understanding of mechanism of stimulation as well.

Joint Inversion of Helicopter-Borne Electromagnetic Data Using Marquardt's Algorithm

The inversion stability of geological data can be enhanced by increasing the number of observation data or improving the accuracy of it. For the purpose of increasing the input parameters, the joint inversion algorithm based on Marquette’s method is introduced to the helicopter-borne electromagnetic system. Since double parameters of both the horizontal coplanar and vertical coaxial coils were taken into account, the stability of the inversion process is greatly improved. In fact, the joint inversion algorithm not only enhances the inversion’s stability, but also overcomes the limitation of the inversion with each single device in order to make the result closer to the real resistivity characteristics

B1 transmit phase gradient coil for single-axis TRASE RF encoding

PurposeTRASE (Transmit Array Spatial Encoding) MRI uses RF transmit phase gradients instead of B0 field gradients for k-space traversal and high-resolution MR image formation. Transmit coil performance is a key determinant of TRASE image quality. The purpose of this work is to design an optimized RF transmit phase gradient array for spatial encoding in a transverse direction (x- or y- axis) for a 0.2T vertical B0 field MRI system, using a single transmitter channel. This requires the generation of two transmit B1 RF fields with uniform amplitude and positive and negative linear phase gradients respectively over the imaging volume. Materials and MethodsA two-element array consisting of a double Maxwell-type coil and a Helmholtz-type coil was designed using 3D field simulations. The phase gradient polarity is set by the relative phase of the RF signals driving the simultaneously energized elements. ResultsField mapping and 1D TRASE imaging experiments confirmed that the constructed coil produced the fields and operated as designed. A substantially larger imaging volume relative to that obtainable from a non-optimized Maxwell-Helmholtz design was achieved. ConclusionThe Maxwell (sine)–Helmholtz (cosine) approach has proven successful for a horizontal phase gradient coil. A similar approach may be useful for other phase-gradient coil designs.

Imaging of 3D electromagnetic data at low-induction numbers

We expressed electromagnetic measurements at low induction numbers as spatial averages of the subsurface electrical conductivity distribution and developed an algorithm for the recovery of the latter in terms of the former. The basis of our approach is an integral equation whose averaging kernel is independent of the conductivity distribution. That is, the recovery of conductivity from the measurements leads to a linear inverse problem. Previous work in one and two dimensions demonstrated that using a kernel independent of conductivity leads to reasonably good results in quantitative interpretations. This study extended the approach to 3D models and to data taken along several profiles over a given area. The algorithm handles vertical and horizontal magnetic dipoles with multiple separations for appropriate depth discrimination. The approximation also handles issues like negative conductivity measurements, which commonly appear when crossing near-surface conductors. This happens particularly when using vertical magnetic dipoles; whose averaging kernel has significant negative weights in the space between the dipoles, something that does not happen for the horizontal dipoles. In general, the more complex the kernel, the more complicated the signature of any given anomaly. This makes qualitative interpretations of pseudosections somewhat difficult when dealing with more than one conductive or resistive body. The algorithm was validated using synthetic data for imaging data from horizontal or vertical coils or from a combination of them. Imaging of field data from a mine tailings site recovered a shallow 3D conductive anomaly associated with the tailings.

Development of Corrector Magnet Designs for the SIS 300

As part of participation in project FAIR, IHEP has been developing designs of fast-cycling superconducting corrector magnets for the SIS 300 ring. There will be four types of corrector magnets: a steering dipole with vertical and horizontal dipole coils, a chromaticity sextupole, a resonance sextupole and a multipole magnet, consisting of quadrupole, sextupole and octupole coils. The paper presents requirements for the magnets, optimizations of the cross-section and 3D geometries, main magnetic characteristics, selection of the mechanical structure of the magnet to confine all forces affecting the coil. Since the magnets are fast-cycling, special attention is given to the choice of the current-carrying element by taking into account quench processes. Numerical analysis of AC losses and magnet temperature margin will also be presented.

Comparison of Geonics EM38 and Dualem 1S electromagnetic induction sensors for the measurement of salinity and other soil properties

AbstractThe electromagnetic induction (EMI) Geonics EM38 (G‐EM38) and Dualem 1S (D‐1S) sensors are used frequently for assessment of soil salinity and other soil characteristics in irrigated agriculture. We compared these two sensors to determine whether they could be used interchangeably for the measurement of apparent soil electrical conductivity (ECa) in horizontal (ECa‐h) and vertical (ECa‐v) coil receiver modes. Readings were taken at 201 locations identified in three irrigation districts in both modes, and statistical comparisons were made on the raw data and from maps of a 2‐ha irrigated field made using 1680 horizontal mode readings. Both sensors gave the same ECa‐v readings (mean G‐EM38 and D‐1S difference = 0), whereas the ECa‐h readings were slightly greater with the Geonics EM38 than with the Dualem D‐1S (mean difference = 0.075 and 0.05 dS/m for the 201 and 1680 observations, respectively). The degree of coincidence between both sensors for soil profile ECa classification was acceptable: 82% for normal profiles (i.e. ECa‐h/ECa‐v < 0.9) and 90% for inverted profiles (i.e. ECa‐h/ECa‐v > 1.1). In practical terms, Geonics EM38 and Dualem 1S sensors could be used interchangeably with similar or very close results.

Three‐Dimensional Sensitivity Distribution and Sample Volume of Low‐Induction‐Number Electromagnetic‐Induction Instruments

There is an ongoing effort to improve the understanding of the correlation of soil properties with apparent soil electrical conductivity as measured by low‐induction‐number electromagnetic‐induction (LIN FEM) instruments. At a minimum, the dimensions of LIN FEM instruments' sample volume, the spatial distribution of sensitivity within that volume, and implications for surveying and analyses must be clearly defined and discussed. Therefore, a series of numerical simulations was done in which a conductive perturbation was moved systematically through homogeneous soil to elucidate the three‐dimensional sample volume of LIN FEM instruments. For a small perturbation with electrical conductivity similar to that of the soil, instrument response is a measure of local sensitivity (LS). Our results indicate that LS depends strongly on the orientation of the instrument's transmitter and receiver coils and includes regions of both positive and negative LS. Integration of the absolute value of LS from highest to lowest was used to contour cumulative sensitivity (CS). The 90% CS contour was used to define the sample volume. For both horizontal and vertical coplanar coil orientations, the longest dimension of the sample volume was at the surface along the main instrument axis with a length of about four times the intercoil spacing (s) with maximum thicknesses of about 1 and 0.3 s, respectively. The imaged distribution of spatial sensitivity within the sample volume is highly complex and should be considered in conjunction with the expected scale of heterogeneity before the use and interpretation of LIN FEM for mapping and profiling.