Equidistant Arrangement Research Articles

Performance Investigation of a Novel Staggered Round Table Channel for Proton Exchange Membrane Fuel Cells

Based on the internal mass transfer of a proton exchange membrane fuel cell (PEMFC), a novel staggered round table channel is proposed, namely, round table stoppers are arranged on both sides of the channel and in the direction of gas flow. The study systematically investigates the effects of various structural parameters on the PEMFC performance, including the arrangement of round tables on both sides of the channel, radius, degree of sparseness, and number. It is found that the staggered arrangement can improve the cell performance more significantly, and the current density can be increased by 5.0% compared with the direct channel. With the proper increase of the radius and number of round tables, the round table stopper forces the reactant to diffuse downward and improves the uniformity of reactant distribution. Compared with other sparsity, the equidistant arrangement of stoppers in the channel is conductive to accelerating the convective mass transfer and drainage characteristics of the cell. As shown by numerical analysis results, the performance and dewatering efficiency of PEMFC are the best when the round tables on both sides are staggered, the radius is 0.65 mm, the number is 10, and the round table in the channel is arranged equidistantly.

Radical cations of chalcogenanthrenes with halogenido metalate anions. Part I: tetramethoxythianthrene

Abstract The electron-rich molecule tetramethoxythianthrene TMO-TA can readily be oxidized to the radical cation using various transition metal halides in acetonitrile as solvent. Reactions with CuBr2, FeCl3, AuCl3, NbCl5, and CuCl2 yield dark blue or black crystals of [TMO-TA]2[CuBr4] (2), [TMO-TA][FeCl4] · CH3CN (3), [TMO-TA][AuCl4] (4), [TMO-TA][NbCl6] · CH3CN (6), and [TMO-TA]5[Cu2Cl6]2 · 2 CH3CN (7). [TMO-TA]2[Ta2OF10] (5) was obtained by anodic oxidation of TMO-TA in the presence of (Nbu4)2[Ta2OF10] as electrolyte. Using mercury(II) bromide, no redox reaction occurs. Instead, the colorless complex [HgBr2(TMO-TA)] (1) is formed. In the crystal structures of the compounds 2–7, the almost planar radical cations show different types of arrangements. Pair formation of the [TMO-TA]•+ radicals to [TMO-TA]2 2+ dimers with the typical intra-pair S⋯S bonds of 3.1–3.2 Å lengths is predominant. Compounds 6 and 7 contain stacks of planar TMO-TA molecules in equidistant arrangement without pair formation and the unique feature of rotation of each adjacent cation by about 30°. Compounds 2, 5, and 7 are electrical semiconductors with band gaps between 0.62 and 1.4 eV, reflecting the arrangement of the radical cations. While 5 is diamagnetic, the magnetic momenta of 2 and 7 correspond only to the expected paramagnetic momenta of magnetically dilute Cu2+ ions. Electrons on the organic radicals are strongly paired in all compounds.

The processing method of the parameters of the beam pattern of phased array antennas

The investigation results of the radiation pattern as one of the important parameters of the phased array antenna are presented at the article. Practical results: obtaining skills in using MathCad and researching methods for improving the directional pattern in order to increase the accuracy of determining the goal. The paper presents an algorithm for calculating the radiation pattern of antenna arrays with four modules and a method for improving it. Software and mathematical results are available in the Internet for free, that allows anyone to do similar work to confirm the calculations and conclusions. The results could be used at students practice in technical universities while studying in specialties related to radio electronic engineering in courses connected with study of the design principles of antenna systems with an equidistant arrangement of elements. Publication could be recommended as methodical manual to students for homework solving or laboratory work using specialized MathCad software.

Nonlinear-Fourier-Transform-Based Dynamic Analyses on the Multiple Cavity Solitons in Kerr Microresonators

The Kerr microresonators have aroused widespread interests for their ultrahigh integration, compatible fabrication and ultralow energy consumption. Similar to the traditional mode-locked fiber lasers, the microresontors can sustain the generation of dissipative solitons called cavity solitons relying on the double balance of gain and loss as well as nonlinearity and dispersion. The state of multiple solitons is common in the microresonator with anomalous dispersion. In particular, an ideal state named as soliton crystals is obtained when the multiple solitons have a equidistant arrangement. And recent experiments have successfullly observed soliton crystals in the Kerr microresonators. To intuitively reveal the formation and evolution dynamics of the multiple solitons and get insight into the underlying physical mechanisms of soliton crystals, we applied the nonlinear Fourier transform to project these states into nonlinear discrete spectrum. The discrete spectra of single soliton with different modulated background waves have been displayed, which can help distinguish different optical components. Then, the nonlinear spectrum evolution of normal multiple solitons state shows the typical nonlinear states of the intracavity field. And the equidistant solitons have the effects of power enhancement, whose spectral intensity is several times that of a single soliton state. Comparing with the discrete spectrum of the equidistant solitons, the solitons inside the soliton crystals interact with each other by the modulated background. Our results suggest that the nonlinear Fourier transform is a powerful technique to characterize soliton dynamics in the Kerr microresonator, which provides a new perspective to understand the interactions of cavity solitons.

Application and discussion of the borehole radial deformation method in deep borehole geostress measurement

Geostress is an important parameter in rock-related fields, such as civil engineering, mining engineering, and energy engineering. There are kinds of methods for geostress measurement; however, many methods still have some limitations, especially when facing deep vertical boreholes. In this paper, we studied the characteristics of borehole radial deformation under the action of geostress. First, the rule of borehole radial deformation under the action of a two-dimensional geostress was studied, and the shape of the borehole radial changes to an ellipse under the action of geostress was proved. We derived the relationship between the magnitude of principal stresses and the parameters of the borehole ellipse, revealing the rule that the principal axis direction of the borehole ellipse is the direction of principal stress, which is the theoretical basis for the geostress calculation method based on borehole radial deformation measurement. Furthermore, we developed an apparatus that can simultaneously measure the changes in borehole diameters in multi-directions. The apparatus was designed with a multi-contact equidistant arrangement, micro-optical imaging measurement, electronic compass azimuth measurement, etc. It can adapt to the complex testing environment of deep boreholes and realize real-time monitoring of the borehole deformation process. Indoor tests were carried out to verify the working performance of the apparatus. The results showed that the measuring accuracy of the apparatus can reach 6.987 μm, meeting the requirement of geostress measurement. Also, the results are well consistent with the loading force and direction of the testing machine. A field test was carried out in a deep borehole, and the borehole radial deformation data were obtained in the process of stress relief. The feasibility of the instrument and method was verified by comparison with the hydraulic fracturing method. This paper provides a new idea and method for geostress measurement, especially in deep vertical boreholes.

The processing method of the parameters of the beam pattern of phased array antennas

The investigation results of the radiation pattern as one of the important parameters of the phased array antenna are presented at the article. Practical results: obtaining skills in using MathCad and researching methods for improving the directional pattern in order to increase the accuracy of determining the goal. The paper presents an algorithm for calculating the radiation pattern of antenna arrays with four modules and a method for improving it. Software and mathematical results are available in the Internet for free, that allows anyone to do similar work to confirm the calculations and conclusions. The results could be used at students practice in technical universities while studying in specialties related to radio electronic engineering in courses connected with study of the design principles of antenna systems with an equidistant arrangement of elements. Publication could be recommended as methodical manual to students for homework solving or laboratory work using specialized MathCad software.

On the features of breaking a microjet of dilute polymer solution into main and satellite microdroplets under external vibration perturbation

An experimental study of the morphology of the laminar microjet flow of diluted aqueous solutions of sodium alginate without and with the addition of hydroxyethyl cellulose after a nozzle subject to external vibration stimulation by the action of the reverse piezoelectric effect was carried out. We studied the influence of the polymer concentration in the solution (0.5-5 mg/ml), the flow rate of the liquid (4-26 ml/min), and the frequency of the current of external perturbation (0-1.2 kHz) on the capillary crushing of the microjet with a diameter of about 210 um in the range of Ohnesorge numbers from 0.046 to 1.88 and Reynolds numbers 0.7 to 470. The modes of microjet flow and crushing on microdroplets with indication of boundaries of transitions between them are selected, and a general map of modes is built. Taking into account the polymer concentration in the solution, the dependence of the microjet fracture length on its velocity is shown. The conditions of monodisperse microjet destruction with equidistant arrangement of the main microdroplets in the flow are determined, which are related to an optimal balance between the molecular mass of the polymer in the solution, the intensity of external disturbance and the time of stress relaxation in polymer viscoelastic microjets. The role of formation of structures such as "beads-on-filament" in capillary destruction of microjet with identification of cases of absence of occurrence of "satellite" microdroplets from liquid threads between the main microdroplets has been studied. The results are applied to technologies based on in-air microfluidics (bioengineering and additive technologies), dealing with heterogeneous fluids with viscoelastic properties. Keywords: Plateau-Rayleigh instability, reverse piezoelectric effect, monodisperse breakup, relaxation time, microjet flow.

Особенности разрушения микроструи разбавленного полимерного раствора на основные и спутниковые микрокапли под действием внешнего вибрационного воздействия

An experimental study of the morphology of the laminar microjet flow of diluted aqueous solutions of sodium alginate without and with the addition of hydroxyethyl cellulose after a nozzle subject to external vibration stimulation by the action of the reverse piezoelectric effect was carried out. We studied the influence of the polymer concentration in the solution (0.5-5 mg/ml), the flow rate of the liquid (4-26 ml/min), and the frequency of the current of external perturbation (0-1.2 kHz) on the capillary crushing of the microjet with a diameter of about 210 um in the range of Ohnesorge numbers from 0.046 to 1.88 and Reynolds numbers 0.7 to 470. The modes of microjet flow and crushing on microdroplets with indication of boundaries of transitions between them are selected, and a general map of modes is built. Taking into account the polymer concentration in the solution, the dependence of the microjet fracture length on its velocity is shown. The conditions of monodisperse microjet destruction with equidistant arrangement of the main microdroplets in the flow are determined, which are related to an optimal balance between the molecular mass of the polymer in the solution, the intensity of external disturbance and the time of stress relaxation in polymer viscoelastic microjets. The role of formation of structures such as «beads-on-filament» in capillary destruction of microjet with identification of cases of absence of occurrence of «satellite» microdroplets from liquid threads between the main microdroplets has been studied. The results are applied to technologies based on in-air microfluidics (bioengineering and additive technologies), dealing with heterogeneous fluids with viscoelastic properties.

Increasing soybean productivity by plant equidistant arrangements and modification of technology levels of cropping systems

The arrangement of soybean plants defines their ability to recognize the environment and improve their abiotic and biotic interactions with it. This study aimed to evaluate the effect of planting arrangements associated to two distinct crop systems (high technological level or conventional crop level) for the soybean varieties 8473 RSF and AS 3730, to evaluate the plant performance and productivity in the field. A double factorial scheme was used with two varieties and six spatial arrangements. Two experiments were conducted during the 2017–2018 crop season: the first was based on standard cultivation of the Brazilian Cerrado (without irrigation systems and adequate fertilizer), whereas the second utilized high technology (irrigation systems and increased fertilizer). The morphophysiological parameters, normalized difference vegetation index (NDVI), leaf pigment content and crop yield parameters were evaluated. Our study pointed out the positive responses for both cultivated varieties and two technological levels adopted cultivated under equidistant arrangement and high density. The leaf area index, leaf pigment content, NDVI, and crop production showed substantial responses under different equidistant arrangements. Therefore, this procedure requires adjustments in the level of cultivation technology and identification of the most suitable soybean variety.

Microstrip Quazi-Elliptic Bandpass Filter With Two Pairs of Antiparallel Mixed-Coupled SIRs

An analysis of the second-order mixed-coupled bandpass filter (BPF) of a general form is carried out. The resonators in this BPF are presented by a resonant frequency $f_{0}$ and a susceptance slope parameter $b$ . The position of the transmission zero (TZ) generated by the mixed coupling is determined. A correspondence is established between the mixed coupling representation as the sum of magnetic $K_{\mathrm{ m}}$ and electric $K_{\mathrm{ e}}$ components and the linear representation form $m (\Omega) = m_{0} {-} a \,\,\Omega $ . It is shown that the slope of the frequency dependence $m(\Omega $ ) is negative. The conditions for equidistant arrangement of two TZs in BPF with mixed couplings between adjacent resonators are formulated. A fourth-order microstrip quazi-elliptic BPF with two pairs of antiparallel mixed-coupled stepped-impedance resonators (SIRs) is proposed. It reduces the parasitic interaction between nonadjacent resonators and makes it possible to obtain the required frequency responses more accurately. The results of the measurements and simulation are presented.

Observation of Flow and Discharge through Multi Gating System

In the case of transport industries, engineering products made by the method of casting as a traditional. it is an effective design of the feeding system. To address the bizarre of gating system by experimental investigations: Centre Sprue Parallel Connection (CSPC) and Centre Spure Runner Extension Parallel Connection (CS-RE-PC). By using water medium to analyse velocity and discharge. Congest result can be applicable to any one metal which is a like kinematic viscosity of water. By shutting disguised gates were enlist data in a various time. due to the equidistant arrangement, a uniform flow throughout the cavity. Almost in all the cases, the higher or equal deport was found in gating design CS-RE-PC and useful to improve optimum runner and find the gate in the multi- cavity system.

Temporal-spatial cross-correlation analysis of non-stationary near-surface wind speed time series

Temporal-spatial cross-correlation analysis of non-stationary wind speed time series plays a crucial role in wind field reconstruction as well as in wind pattern recognition. Firstly, the near-surface wind speed time series recorded at different locations are studied using the detrended fluctuation analysis (DFA), and the corresponding scaling exponents are larger than 1. This indicates that all these wind speed time series have non-stationary characteristics. Secondly, concerning this special feature (i.e., non-stationarity) of wind signals, a cross-correlation analysis method, namely detrended cross-correlation analysis (DCCA) coefficient, is employed to evaluate the temporal-spatial cross-correlations between non-stationary time series of different anemometer pairs. Finally, experiments on ten wind speed data synchronously collected by the ten anemometers with equidistant arrangement illustrate that the method of DCCA cross-correlation coefficient can accurately analyze full-scale temporal-spatial cross-correlation between non-stationary time series and also can easily identify the seasonal component, while three traditional cross-correlation techniques (i.e., Pearson coefficient, cross-correlation function, and DCCA method) cannot give us these information directly.

Numerical Analysis of Shell-and-Tube Type Latent Thermal Energy Storage Performance with Different Arrangements of Circular Fins

Latent thermal energy storage (LTS) systems are versatile due to their high-energy storage density within a small temperature range. In shell-and-tube type storage systems fins can be used in order to achieve enhanced charging and discharging power. Typically, circular fins are evenly distributed over the length of the heat exchanger pipe. However, it is yet to be proven that this allocation is the most suitable for every kind of system and application. Consequently, within this paper, a simulation model was developed in order to examine the effect of different fin distributions on the performance of shell-and-tube type latent thermal storage units at discharge. The model was set up in MATLAB Simulink R2015b (The MathWorks, Inc., Natick, MA, USA) based on the enthalpy method and validated by a reference model designed in ANSYS Fluent 15.0 (ANSYS, Inc., Canonsburg, PA, USA). The fin density of the heat exchanger pipe was increased towards the pipe outlet. This concentration of fins was implemented linearly, exponentially or suddenly with the total number of fins remaining constant during the variation of fin allocations. Results show that there is an influence of fin allocation on storage performance. However, the average storage performance at total discharge only increased by three percent with the best allocation compared to an equidistant arrangement.

LTE OFDM 시스템에서의 기준 심볼 배치

For the purpose of estimation of time variant frequency selective transmission channels, reference symbols are usually employed. The bit error performance of LTE OFDM systems is analyzed in the case of LTE standard reference symbol arrangement. Results show that LTE OFDM system with this LTE reference symbol arrangement is robust against Doppler time variant fading. However, the performance of that system is degraded due to channel estimation error in frequency domain. An equidistant arrangement with a diamond shape structure of reference symbols, however having 4 subcarriers distance in frequency domain, is suggested for the optimal channel estimation.

Harmonic passive mode locking of bound-soliton structures in fiber lasers

It has been shown by numerical simulation that additional inertial nonlinearity of the refractive index results in repulsion of solitons in multi-pulse passive mode-locked fiber lasers if the intersoliton distance is sufficiently large. At the same time, closely spaced solitons are attracted to each other. It has been found that the combination of these properties of soliton interaction can lead to harmonic passive mode locking of identical structures of bound solitons (generation with an equidistant arrangement of soliton structures in the laser cavity). These properties of soliton interaction are caused by the asymmetry of the wings of an individual soliton, which manifests itself as the asymmetry of Kelly's spectral peaks and is due to the inertial nonlinearity of the refractive index. Other possible mechanisms of this asymmetry are also discussed.

SAW radio-frequency identification tag for the 6-GHz band

A SAW radio-frequency identification (RFID) tag has been investigated theoretically and experimentally in the 6-GHz frequency band. In the calculations, the finite thickness of the electrodes, the difference between the acoustic properties of thin-film and bulk aluminum, and the bulk scattering of the SAW energy by the electrodes are taken into account. The computed test RFID tag (with equidistant arrangement of signal reflectors) has been manufactured with the use of electron-beam lithography. It is shown that the measured and calculated RFID-tag time responses to the interrogating pulse are in good agreement and the code-pulse loss level is 50–55 dB.

Modal Analysis around the Sun Wheel Non Equidistant Arrangement of Double Branch

In this paper, dynamic model of two stage power branch double wide helical gear planetary drive system based on complex, in-depth study of the natural vibration characteristic. Starting from the first star and second planetary gear around the sun wheel non equidistant arrangement in the respective gear train, calculating modal analysis of characteristics of the system, so as to understand the mechanism of the system vibration, to provide theoretical guidance for the design of underwater device two power branch double wide helical planetary composite transmission system. At the same time to improve the dynamic characteristics of the device structure of underwater engineering significance.

Multi‐step routes of capuchin monkeys in a laser pointer traveling salesman task

Prior studies have claimed that nonhuman primates plan their routes multiple steps in advance. However, a recent reexamination of multi-step route planning in nonhuman primates indicated that there is no evidence for planning more than one step ahead. We tested multi-step route planning in capuchin monkeys using a pointing device to "travel" to distal targets while stationary. This device enabled us to determine whether capuchins distinguish the spatial relationship between goals and themselves and spatial relationships between goals and the laser dot, allocentrically. In Experiment 1, two subjects were presented with identical food items in Near-Far (one item nearer to subject) and Equidistant (both items equidistant from subject) conditions with a laser dot visible between the items. Subjects moved the laser dot to the items using a joystick. In the Near-Far condition, one subject demonstrated a bias for items closest to self but the other subject chose efficiently. In the second experiment, subjects retrieved three food items in similar Near-Far and Equidistant arrangements. Both subjects preferred food items nearest the laser dot and showed no evidence of multi-step route planning. We conclude that these capuchins do not make choices on the basis of multi-step look ahead strategies.

Nature of soliton interaction in fiber lasers with continuous external optical injection

It has been shown by numerical simulation that the nonlinear interaction between a laser soliton and an injected monochromatic cw results in their phase locking. As a consequence, the velocity of the soliton begins to depend on the amplitude and frequency of the injected radiation. It has been found that if the frequency of the external signal coincides with the frequency of the dispersive waves emitted by solitons in a laser cavity with lumped intracavity elements, a mechanism for controlling long-range soliton interaction occurs. This mechanism is related to the interference between the injected wave and the dispersive waves involved in the strong long-range interaction between solitons. We have demonstrated the mechanism of soliton-soliton repulsion and, as its consequence, the occurrence of harmonic passive mode locking (multipulse generation with an equidistant arrangement of identical solitons in the laser cavity).

Laser Profile Scanner Application for Micro Part Detection

Due to size effects production processes for macro parts are often not applicable to micro production. Especially the handling is more complicated. The approach to overcome these problems is to resize the parts to the macro world by producing them in linked parts. These structures use the base material as a substrate which keeps the micro parts interconnected. The small tolerances for micro parts demand a high precision positioning for the subsequent processing. An equidistant arrangement cannot be assured by the manufacturing processes. The micro parts must be identified within the linked parts by characteristic geometrical features and referenced separately with respect to the feed system. For this task the application of a laser profile scanner is investigated. For the data evaluation and the recognition of typical geometrical features a real-time capable algorithm with sufficient robustness against noise and measuring errors is developed. To validate the function of the algorithm test measurements are performed and compared to reference measurements done by microscopy.