Plane Configuration Research Articles

Pfaffian bundles on cubic surfaces and configurations of planes

We construct a canonical birational map between the moduli space of Pfaffian vector bundles on a cubic surface and the space of complete pentahedra inscribed in the cubic surface. The universal situation is also considered and we obtain a rationality result. As a by-product, we provide an explicit normal form for five general lines in \(\mathbb {P}_5\). Applications to the geometry of Palatini threefolds and Debarre–Voisin Hyper-Kahler manifolds are also discussed.

Microstructural Effects in Textured Neodymium Doped Ceria

Neodymium doped ceria (NDC) is a promising candidate for use as an electrolyte in a solid oxide fuel cell (SOFC) due to its high ionic conductivity, low electronic conductivity, and good sinterability and stability. It is well known that grain size and grain boundary effects can significantly impact the observed ionic conductivity of ceria in the bulk and particularly in thin films. This work focuses on the influence grain size (film thickness) and grain boundary configuration have on the ionic conductivity of NDC. To this end, textured NDC thin films of varying thicknesses and grain sizes were grown on sapphire substrates using pulsed laser deposition (PLD). We will present broadband impedance data analysis on across plane and in-plane electrode configurations collected as a function of temperature. The separate effects of film thickness, grain size, and grain boundary on the observed ionic conductivity will be discussed based on the contrasting data from the two measurement configurations.

Sinusoidal buckling of a thin rod with connectors constrained in a cylinder

Kinds of tubular strings with connectors are widely used in petroleum exploration and development field. In previous research, tubular strings are usually treated as homogeneous thin elastic rods constrained in a cylinder and few studies have been made on the effect of connectors.This paper builds a model to describe the sinusoidal buckling behaviors of a rod with connectors. The three-dimensional buckling problem is divided into two lateral buckling problems in two mutual-perpendicular planes and the buckling solutions are obtained by solving the two lateral buckling equations.There are two buckling states for the rod, including initial plane configuration and sinusoidal configuration. And there are three contact cases between the rod and the cylinder, including no contact, point contact and wrap contact. The critical condition from initial plane configuration to sinusoidal configuration is approximately obtained from the results of no connector rod, and the critical conditions between different contact states are obtained by solving the model numerically. The effects of geometric parameters of the connectors and weight of the rod on critical conditions are analyzed. For the no contact and point contact cases, the deflection curves of a rod in the initial plane configuration and sinusoidal configuration are calculated in this paper. The effects of connectors on bending stress and contact force of the rod are analyzed.The results indicate that buckling states and contact states depend on the combination of the dimensionless axial compression Ku, the ratio of rod/cylinder radial clearance to connector/cylinder radial clearance Kr and the dimensionless weight per unit length of the rod μ. Compared with the no connector case, connectors have a great influence on the deflection curve, bending moment and contact force of the rod. All the results from the model indicate that the effects of connectors cannot be ignored in sinusoidal buckling analyses.

Synthesis, structure analysis and antibacterial activity of N-[5-dehydroabietyl-[1,3,4]thiadiazol-2-yl]-aromatic amide derivatives

A series of N-[5-dehydroabietyl-[1,3,4]thiadiazol-2-yl]-aromatic amide derivatives were synthesized from dehydroabietic acid. Their structures were characterized by IR, 1H NMR, MS, elemental analysis and single crystal X-ray diffraction. Four six-membered rings of 2b exhibited plane, half-chair and chair configurations, respectively. The antibacterial activity of these newly synthesized N-[5-dehydroabietyl-[1,3,4]thiadiazol-2-yl]-aromatic amides derivatives against Gram-negative bacteria and Gram-positive bacteria was also investigated using the minimum inhibition concentration method. Preliminary results indicated that five compounds displayed better antibacterial activity against Pseudomonas aeruginosa and Escherichia aerogenes compared to commercially available antibacterial agents of Bromogeramine and Ampicillin sodium.

Mass transfer in back-to-back elbows arranged in an out of plane configuration

Flow-Accelerated Corrosion (FAC) is a major degradation mechanism affecting carbon steel piping systems in nuclear power plants (NPPs). Flow and mass transfer conditions determine the local distribution of wall thinning, even though chemistry and materials determine the overall potential for FAC. Different localized thinning rates in back-to-back elbow configurations between the first and second elbows have been noted at NPPs, and this difference depends on the distance between elbows, flow conditions, and the configuration of the back-to-back elbows (S-, C-, or out of plane). This paper will focus on mass transfer measurements for back-to-back elbows arranged in an out of plane configuration for different elbow separation distances under single-phase flow conditions. The mass transfer measurements were performed using a mass dissolution technique of gypsum test sections in water. The experiments were performed at a Reynolds number of 70,000 and a resulting Schmidt number of 1280, which is similar to that for the diffusion of the iron magnetite layer of carbon steel piping in water, providing a mass transfer environment analogous to that in NPPs. Experiments were performed with 0, 1, 2 and 5 pipe diameters in length between the elbows. The mass transfer results show regions of higher mass transfer in the second elbow in comparison to the first elbow. The maximum mass transfer enhancement factor decreased from 2.7 to 2.1 as the separation distance increased from 0 to 5 pipe diameters. Flow streaks on the second elbow surface indicated swirling flow and its strength decreased with increasing separation distances. The relative roughness in the upstream pipe was found to be 0.003–0.004. The roughness level in the second elbow is 1.5 times higher than the upstream pipe and decreases with increasing bend separation distance.

Long-wave Raman spectra of some normal alcohols

Long-wave Raman spectra of some normal alcohols (from n-pentanol to n-decanol) in the liquid phase were registered. The regularities in the dependencies of Raman bands frequencies on the number of carbon atoms in the hydrocarbon chain were deduced. The calculations of Raman spectra of the studied molecules, their equilibrium structures and possible conformers were carried out in the approximation B3LYP/cc-pVDZ. These results in combination with the analysis of literature data allowed to explain the observed regularities in Raman band positions in the spectral range of 200–600сm−1 and their shifts upon increasing length of the chains. It was found that the plane configurations dominate in the liquid phase for molecules with short- and moderate-chain lengths. The elongation of the chain leads to the decrease of the fraction of plane conformers and in n-decanol the plane structure is completely absent.

Rotation and Turbulent Instability in Peripheral Heavy Ion Collisions

In recent years fluid dynamical processes became a dominant direction of re- search in high energy heavy ion reactions. The Quark-gluon Plasma formed in these reactions has low viscosity, which leads to significant fluctuations and special instabili- ties or flow patterns. One has to study and separate these two effects, but this is not done yet in a systematic way. This presentation presents the most interesting collective flow instabilities, their possible ways of detection and separation form random fluctuations arising from the randomness of the initial configuration in the transverse plane.

A Near-Zero Refractive Index Meta-Surface Structure for Antenna Performance Improvement

A new meta-surface structure (MSS) with a near-zero refractive index (NZRI) is proposed to enhance the performance of a square loop antenna array. The main challenge to improve the antenna performance is increment of the overall antenna volume that is mitigated by assimilating the planar NZRI MSS at the back of the antenna structure. The proposed NZRI MSS-loaded CPW-fed (Co-Planar Waveguide) four-element array antenna is designed on ceramic-bioplastic-ceramic sandwich substrate using high-frequency structure simulator (HFSS), a finite-element-method-based simulation tool. The gain and directivity of the antenna are significantly enhanced by incorporating the NZRI MSS with a 7 × 6 set of elements at the back of the antenna structure. Measurement results show that the maximum gains of the antenna increased from 6.21 dBi to 8.25 dBi, from 6.52 dBi to 9.05 dBi and from 10.54 dBi to 12.15 dBi in the first, second and third bands, respectively. The effect of the slot configuration in the ground plane on the reflection coefficient of the antenna was analyzed and optimized. The overall performance makes the proposed antenna appropriate for UHFFM (Ultra High Frequency Frequency Modulation) telemetry-based space applications as well as mobile satellite, microwave radiometry and radio astronomy applications.

Small artificial magnetic conductor backed log‐periodic microstrip patch antenna

An artificial magnetic conductor (AMC) backed reduced-size log-periodic microstrip patch antenna (LPMA) is presented. To maintain the broadband performance of the LPMA, the AMC ground plane was modified to exhibit a log-periodic structure. Specifically, an AMC ground plane configuration was realised over 0.889 mm thick εr = 10.2 Rogers 6010.2LM substrate for an LPMA printed over 1.524 mm thick εr = 2.94 Rogers 6002 substrate. The AMC-backed LPMA is measured to operate from 5.3 to 8 GHz with linearly polarised broadside radiation, performing with 21% reduced size as compared with a conventional LPMA designed over the identical substrate stack-up.

On arithmetical functions having constant values in some domain

This paper shows that any completely additive complex valued function over a principal configuration in the complex plane, having constant values in some discs, is the identically zero function. In other words, there exists no non-trivial completely additive complex valued function over a principal configuration in \(\mathbb{C}\) which assumes constant values in some domain.

Efficient DC Analysis of Power Planes Using Contour Integral Method With Circular Elements

Contour integral method, well-known for the analysis of 2-D full-wave effects on power planes, is extended here for the computation of DC resistances of power planes. In particular, circular elements, e.g., vias and antipad holes, are treated using cylindrical modal expansion functions, which leads to a more efficient and accurate calculation than the conventional implementation by the linear discretization. For individual power planes, the method produces a resistor network consisting of only the nodes that are associated with power or ground vias, which can be further employed to formulate solutions for complete multilayer structures. The method is applied to several power plane configurations and results are validated by a 3-D finite element method solver. The efficiency of the extended method is analyzed and a reduction of the number of unknowns by a factor of four for the circular elements can be expected by the modal expansion. Good accuracy can be achieved by including up to the second higher order mode for dense clusters of antipad holes.

Electroconvection between coaxial cylinders of arbitrary ratio subjected to strong unipolar injection

Abstract This study deals with the electroconvection phenomenon that takes place in a dielectric liquid layer placed between two annular electrodes and subjected to the action of an electric field. The full set of governing equations describing the combined Electro-Hydro-Dynamic (EHD) flow is directly solved with the finite volume method. The development of electroconvective motion is investigated in details in the case of strong injection when the emitter electrode is the inner cylinder. We first examine the stability of such flow. As in the plane–plane configuration we have highlighted the existence of a linear and non-linear critical electric Rayleigh numbers giving rise to a hysteresis loop. The flow structure under the effect of the electric field is analyzed and the distribution of electric charge density is presented. In particular we investigate the effect of various parameters involved in this configuration, such as the radius ratio, injection strength and electric Rayleigh number. A multicellular convective pattern is particularly observed and it is shown that the number of cells is increased when the annular gap is narrower. Finally a significant increase of the rotational speed of the vortex with the electric Rayleigh number is recorded.

W-band Imaging Detector with Incoherent Illumination

A single-pixel imaging detector operating in W-band is described. It is based on a wideband receiving module using direct detecting circuitry and a transmitting unit with a pulse-modulated wideband noise source. The detector consists of a single transmit / receive channel mounted on a programmable scanner in an X-Y plane configuration. A LabView interface integrated with MatLab is employed allowing image continues reconstruction line-by-line. The application of incoherent illumination generated by a frequency-limited noise source improves image quality compared with conventional coherent sources used in active imagers. An image processing algorithm using a binary threshold level is considered with some examples of image reconstruction employing the detector.

Diagnosis of open‐switch faults in variable speed drives by stator current analysis and pattern recognition

This study addresses the problem of detection and isolation of open-switch faults in voltage source inverters by processing the stator current measurements. First, the resulting post-fault trajectories for the stator currents are analytically derived for single and concurrent faults (21 classes) by using Fourier series. This analysis motivated the proposed approach, which is based on the resulting pattern of the stator currents in the dq -frame after a fault, where a histogram of the trajectory is calculated by dividing the plane in 24 equally spaced sectors. From the calculated histogram, a distinctive signature is associated to each fault trajectory in the dq -plane. Single and double faults in the power semi-conductors are analysed that all provide linearly independent signatures for fault isolation. The proposed isolation methodology is independent of the load torque (system disturbance), supply frequency and only requires the information of the stator currents. Furthermore, since the isolation stage is focused on the angle of the current trajectories in the dq -plane, open- and closed-loop configurations of a variable speed drive can be simultaneously handled. Experimental results with a test bench of 3/4 HP induction motor under single and concurrent faults validated the proposed methodology.

Molecular dynamics simulation of twinning in devitrite, Na2Ca3Si6O16

Reports of Type II twins are quite rare for most crystal structures. When they do occur, they are usually one of a number of possible twinning modes observed in a particular material. However, for the triclinic phase devitrite, Na2Ca3Si6O16, which nucleates from commercial soda−lime−silica float glass subjected to suitable heat treatments, the only reported twinning mode to date is a Type II twinning mode. In this study, this Type II twinning mode is first examined by molecular dynamics simulation to determine the lowest energy configuration of perfect twin boundaries for the twin mode. This is then compared with the lowest energy configurations of perfect twin boundaries found for six possible Type I twinning modes for devitrite for which the formal deformation twinning shear is less than 0.6. The most favourable twin plane configuration for the Type II twinning crystallography is shown to produce reasonably low twin boundary energies and sensible predictions for the optimum locations of the twin plane, K 1, and the [1 0 0] rotation axis, η 1, about which the 180° Type II twinning operation takes place. By comparison, all the Type I twinning modes were found to have very energetically unstable atomic configurations, and for each of these twinning modes, the lowest energy configurations found all led to high effective K 1 twin boundary energies relative to perfect crystal. These results therefore provide a rationale for the experimental observation of the particular Type II twinning mode seen in devitrite.

Study on gust alleviation control and wind tunnel test

Aircraft are inevitably affected by gust during flight, which disturbs the regular operations of pilots and worsens the ride quality. In more grievous cases, flight mission cannot be completed and the flight safety may be disserved. In order to improve the ride quality and the fatigue life of the plane structure under the affect of gust, it is necessary to explore and validate the gust alleviation schemes. Through the low-speed wind tunnel test, the gust alleviation active control technology applied to elastic aircraft is studied. For a large-type passenger plane configuration with high aspect ratio wing, a test system was designed and three gust alleviation control schemes with PID controllers were proposed. Finally the gust alleviation control low-speed wind tunnel test was carried out in the FD-09 wind tunnel. Test results showed that at certain speed and gust frequency, all of the 3 control schemes can alleviate the acceleration at fuselage and wing-tip to a certain extent, as well as the bending moment of wing-root. The gust alleviation control scheme, which uses aileron, elevator and canard as control surfaces synthetically, gives the most satisfying gust alleviation effect.

Special Lagrangian conifolds, II: gluing constructions in ℂ m

We prove two gluing theorems for special Lagrangian (SL) conifolds in complex space C^m. Conifolds are a key ingredient in the compactification problem for moduli spaces of compact SLs in Calabi-Yau manifolds. In particular, our theorems yield the first examples of smooth SL conifolds with 3 or more planar ends and the first (non-trivial) examples of SL conifolds which have a conical singularity but are not, globally, cones. We also obtain: (i) a desingularization procedure for transverse intersection and self-intersection points, using "Lawlor necks"; (ii) a construction which completely desingularizes any SL conifold by replacing isolated conical singularities with non-compact asymptotically conical (AC) ends; (iii) a proof that there is no upper bound on the number of AC ends of a SL conifold; (iv) the possibility of replacing a given collection of conical singularities with a completely different collection of conical singularities and of AC ends. As a corollary of (i) we improve a result by Arezzo and Pacard concerning minimal desingularizations of certain configurations of SL planes in C^m, intersecting transversally.

Numerical Simulation of Hypersonic Flow Around an Aerospace Plane by Parallel RANS based CFD

This paper deals with a numerical investigation on a complex geometry aerospace plane configuration with no tail fuselage and leaping triangle wing tip similar to HERMES of France. Two case of numerical simulation which including aerodynamic and aerothermodynamics characteristic. Including two case investigation Numerical simulation two cases were performed for performed for Mach number of 4.97(Re=1.3×107) at angles of attack from -5 deg to 20 deg and 8.04(Re=1.13×107) at angles of attack from -5 deg to 18 deg using parallel Multi-block Structure NS solver. Also three different CPU number are used in the investigation. Comparisons method used between the aerodynamic characteristics and wind tunnel data verify the reliability of the numerical method used for simulating viscous flow around the aerospace plane. Numerical results show that the present method is an effective and powerful analysis tool to predict the hypersonic flow field around a complex geometry.

Effect of Test Method and Needle Plane Configuration on Partial Discharge Inception Voltage Measurement of Mineral Oil based on Weibull Analysis

Abstract The discussion of test method and electrode configuration for Partial Discharge Inception Voltage (PDIV) measurement is continuously developed because the PDIV can be used as indicator to determine condition of insulating liquid. However, many researchers investigate the PDIV using different test method and electrode configurations. This paper discusses the effect of test methods and needle to plane electrode configuration on the PDIV measurement of mineral oil as insulating liquid. The mineral oil that used in experiment test was Nynas Nitro 4000x with water content less than 10 ppm. In experiment, the test circuit was set up according to IEC 60270. The first test method that was carried out in this experiment according to IEC 61294 with ramp rate of test voltage 1 kV/s until PDIV occurred. Meanwhile, a Combine Method as the second test method was used as comparative PDIV test technique for this experiment. With this combine method, the test voltage was applied to the test object with rate 1 kV/s until 70% of the PDIV value obtained from the first test method. Then the test voltage was increased in steps with 1 kV/step with step duration of 1 minute until PDIV obtained with PD charge ≥ 100 pC. The rest time between consecutive tests was 5 minutes. The needle tip radii that used as high voltage electrode were 10 μm and 20 μm, meanwhile brass plane electrode with diameter 50 mm was used as the grounded electrode. In this paper, the electric field stress of the needle to plane electrode was calculated using Finite Element (FEM) simulation with input voltage 100 volt. The test result was analyzed using Weibull distribution to calculate the Cumulative Distribution Function (CDF) and Probability Density Function (PDF) of PDIV value. The calculation results show that the test results agree with Weibull distribution.

Random non‐crossing plane configurations: A conditioned Galton‐Watson tree approach

ABSTRACTWe study various models of random non‐crossing configurations consisting of diagonals of convex polygons, and focus in particular on uniform dissections and non‐crossing trees. For both these models, we prove convergence in distribution towards Aldous’ Brownian triangulation of the disk. In the case of dissections, we also refine the study of the maximal vertex degree and validate a conjecture of Bernasconi, Panagiotou and Steger. Our main tool is the use of an underlying Galton‐Watson tree structure. © 2014 Wiley Periodicals, Inc. Random Struct. Alg., 45, 236–260, 2014