Double Channel Research Articles

Vibrational, non-adiabatic and isotopic effects in the dynamics of the H2 + H2 + → H3 + + H reaction: application to plasma modelling

The title reaction is studied using a quasi-classical trajectory method for collision energies between 0.1 meV and 10 eV, considering the vibrational excitation of H 2 + reactant. A new potential energy surface is developed based on a Neural Network many body correction of a triatomics-in-molecules potential, which significantly improves the accuracy of the potential up to energies of 17 eV, higher than in other previous fits. The effect of the fit accuracy and the non-adiabatic transitions on the dynamics are analysed in detail. The reaction cross section for collision energies above 1 eV increases significantly with the increasing of the vibrational excitation of H 2 + ( v ′ ), for values up to v ′ =6. The total reaction cross section (including the double fragmentation channel) obtained for v ′ =6 matches the new experimental results obtained by Savic, Schlemmer and Gerlich [Chem. Phys. Chem. 21 (13), 1429.1435 (2020). doi:10.1002/cphc.v21.13]. The differences among several experimental setups, for collision energies above 1 eV, showing cross sections scattered/dispersed over a rather wide interval, can be explained by the differences in the vibrational excitations obtained in the formation of H 2 + reactants. On the contrary, for collision energies below 1 eV, the cross section is determined by the long range behaviour of the potential and do not depend strongly on the vibrational state of H 2 + . In addition in this study, the calculated reaction cross sections are used in a plasma model and compared with previous results. We conclude that the efficiency of the formation of H 3 + in the plasma is affected by the potential energy surface used.

Numerical studies on the behavior of cold‐formed double‐channel shear connector

AbstractThe longitudinal shear forces are transferred through mechanical shear connectors at the steel beams and concrete slab intersection in composite beams. The shear connectors can be directly welded to the hot rolled steel beam, which is difficult in thin, cold‐formed steel beams. Thus, a cold‐formed double‐channel shear connector is proposed, and its suitability is investigated in this study. The double channel shear connector is a channel shaped shear connector formed from a flat plat and it is mounted on the flange of steel beam in pairs. The finite element model of the experimental Pushout test assembly was developed with the equivalent numerical constraints and interaction commands in a finite element software (ABAQUS). The developed models were fed with initial imperfection, load slip response, and material nonlinearity to achieve the proper experiment simulation. Initially, the developed models were validated against nine experimental test data reported by authors in the previous study. The parametric study was conducted to assess the behavior of cold‐formed channel shear connectors. The key parameters adopted in this study are the length of the shear connector, the grade of concrete and the grade and thickness of the steel connector. Three common failure patterns were witnessed among 107 numerical models. In this study, the factors influencing the control of failure patterns are presented, along with the factors influencing the shear connector's ultimate capacity.

Study on the structural design and performance of magnetorheological (MR) valve with hybrid supply magnetic source and double annular channels

Valve plays an important role in achieving precise position control for the hydraulic lift system. In order to improve the performance of hydraulic lift in precise motion, this paper proposes an MR valve with hybrid supply magnetic source and double annular channels. In addition, a structural model was established to perform pressure drop analysis. According to its working principle, it is proposed that this MR valve has two channels that work separately. There are three working modes in which the two channels work together, and the pressure drop of the MR valve can be calculated in different ways. Therefore, the MR valve with hybrid supply magnetic source and double annular channel performance test system is constructed, and the magnetic field inside the valve is simulated by performing magnetic field finite element analysis. Finally, a test bench of vehicle maintenance elevators is built to analyze whether the MR valve with hybrid supply magnetic source and double annular channels can achieve accurate control on the vehicle maintenance elevators. According to the experimental and simulation results, the pressure drop of the MR valve with hybrid supply magnetic source and double annular channels is affected by the current and channel operating mode, while the load makes little difference to the pressure drop. The worse the rising response time performance increases with increasing current, but the response time performance decreases without being affected by current. When a current greater than 1.5A is applied to the coil, the response time of the lifting platform is basically maintained at 6 s with the increase of current. The position accuracy is ±1 mm for the experimental platform of the vehicle maintenance lift table based on the MR valve with hybrid supply magnetic source and double annular channel hydraulic system.

Numerical Investigation on Structural Behaviour of Cold Formed Steel Double Channel Hat Section with Two Plates

Numerical Investigation on Structural Behaviour of Cold Formed Steel Double Channel Hat Section with Two Plates

Three-arm endoscopic mucosal resection for gastric adenocarcinoma of fundic gland type.

A 65-year-old man was diagnosed with intramucosal carcinoma by endoscopy and pathological biopsy; the tumor was 10 mm in size and located in the greater curvature of the gastric body ([Fig. 1 a]). It was difficult to perform endoscopic submucosal dissection (ESD) on the greater curvature of the gastric body. We therefore proposed a three-arm endoscopic mucosal resection (TA-EMR) technique in which two nasal oxygen tubes, about 80 cm in length, were taped to the outside of the endoscope to become a double additional working channel (AWC) ([Video 1]).

Influence of FeS2 and FeSi75 in Double-Chamber Sample Cup on Thermal Analysis Curve and Graphite Morphology of Molten Iron

In the production of vermicular graphite cast iron, the allowable range of residual magnesium content in molten iron after treatment is very narrow, amounting to only 0.008%. Therefore, thermal analysis technology was used to quickly evaluate the vermiculation and inoculation level of molten iron at the furnace itself, thus allowing the molten iron to be adjusted in time. The additives in the sample cups play a crucial role in obtaining cooling curves with remarkable characteristics. In this study, either FeS2 or FeSi75 additives were added to one chamber of a double-chamber sample cup made of resin sand, in which the cavities of the double chambers were spherical with diameters of 30 mm. The thermal analysis curves of molten iron in the double-chamber sample cup were acquired using a double channel temperature recorder, and the solidified spherical samples were analyzed quantitatively. The influence of FeS2 or FeSi75 additives on both the cooling curves of molten iron and the graphite morphology were investigated. The experiment’s results indicated that when 0.05% FeS2 is added to one chamber of the sample cup, the cooling curve changes to the solidification pattern of gray cast iron. The continuous increase in the FeS2 additive has little influence on the shape of cooling curves, and the graphite changes form from vermicular to flaked. When the amount of FeS2 is increased from 0.05% to 0.10%, the resulting graphite changes from D-type and E-type to A-type and B-type. When the amount of FeS2 reaches 0.20%, the morphology of graphite is short and thick. With the increase in the amount of FeSi75 additive, the amount of spherical graphite in the sample cup increases gradually, and the vermicularity decreases gradually from 89% to 46%. With the increase in FeSi75 additive from 0 to 0.45%, we observed that the average diameter of graphite decreases from 23 μm to 19 μm and then increases to 22 μm. The eutectic recalescence temperature shows a decreasing trend, and the cooling curve gradually changes from a hypoeutectic to a eutectic pattern. The addition of 0.05% FeS2 or 0.45% FeSi75 to one chamber is more appropriate for a double-chamber sample cup with two spherical cavities with diameters of 30 mm. This lays a foundation for the optimization of additives when using the double-chamber sample cup for thermal analysis of vermicular graphite cast iron.

Studies on the coupling correlation and strain state of AlGaN/GaN double channel heterostructures grown by metal organic chemical vapor deposition

In this work, high quality AlGaN/GaN double channel heterostructures were grown by metal organic chemical vapor deposition and the coupling correlation between the two channels, as well as the strain state of this multilayer structure are investigated in detail. It was revealed that the stronger coupling correlation affect the 2DEG distribution and leads to the lower channel is similar to the upper channel with the thinner thickness of the upper channel. In addition, the impact of the multilayer strain state on the characteristics of double channel heterostructures was discussed. Moreover, the effects of coupling correlation and strain state on the performance of double channel high electron mobility transistor (HEMT) was shown by 2-D simulation. This work is not only beneficial for the further study of the double (multiple) channel heterostructures and devices, but also instructive to the design and realization of the future atomic hyperfine structures of nitride semiconductors.

A double network hydrogel electrolyte-based electrochromic device for enhanced electrochromic performance and lower power consumption

This study aims to investigate the electrochromic behavior of a Y-shaped, water-soluble monosubstituted viologen analog, BPYDB-C6H13, in different electrolyte systems. Two all-in-one gel-type ECDs (CMC-Na-ECD and CMC-Na-PAM-ECD) with CMC-Na hydrogel and CMC-Na-PAM double network hydrogel as the electrolytes and a solution-type ECD (DIW-ECD) were fabricated, and the electrochromic behaviors of BPYDB-C6H13 in different electrolytes were studied. Compared to DIW-ECD, the gel-state ECDs, especially CMC-Na-PAM-ECD with double network channel, showed enhanced cycling stability (retaining of the initial optical contrast after 12,000 s: 99.0% versus 95.5%), improved coloration efficiency (168.5 cm2/C versus 64.3 cm2/C), lower power consumption (0.55 mW/cm2 versus 2.11 mW/cm2), and longer memory time, because CMC-Na-PAM hydrogel had a larger pore size and a smoother transfer path than CMC-Na, thus reduced the path of charge transfer, and enhanced the ionic conductivity. The characteristics of easy-to-make, better electrochromic performance, and ultra-low power consumption make this gel-state ECD a promising candidate for applications in the fields of electronic paper, smart windows, displays, etc.

Effects of equivalence ratios on the normal and inverse diffusion flame of acid gas combustion in the pure oxygen atmosphere

The experimental studies on the effect of equivalence ratios to the acid gas (H2S and CO2) combustion in the pure oxygen atmosphere was presented in a coaxial jet double channel burner. Three equivalence ratios (Φ = 0.8, 1.0 and 1.5) are examined to analyze the distribution of the flame temperature and gas composition in the normal and inverse diffusion flame along central axial (R = 0.0) and axial line at 3 mm (R = 0.75) in radial direction. The results revealed that acid gas combustion mainly occurred chemical decomposition of H2S and oxidation of H2S and H2 at R = 0.0, while mainly occurred H2S and H2 oxidation at R = 0.75 in the normal diffusion flame. Reducing Φ increased the flame temperature and it is higher at R = 0 than that at R = 0.75 because of heat loss. It also increased the volume fraction of CO, H2 and COS in the flame combustion area, while decreased downstream reactor because of occurring oxidation. CO was formed by the reaction of CO2 and H, and H2 primarily derived from chemical decomposition of H2S. COS was generated by the reaction of CO2 with SH, H2S and S as well as the reaction of CO with SO and SH at R = 0.0, while was mainly formed by the reaction of CO with SO and SH at R = 0.75. H2S mainly occurred the oxidation in the inverse diffusion flame. The temperature at R = 0.0 was still higher than that at R = 0.75, and it was higher than that in the normal diffusion flame in the combustion area. Increasing Φ promoted the formation of CO, H2 and COS, and each gas under Φ of 1.5 was higher significantly. The Φ had no significant effect on the distribution of SO2 compared to the normal diffusion flame, but changed the distribution of CO, H2 and COS. It can be inferred that the content of CO, H2 and COS will be more higher under Claus condition in the inverse diffusion flame.

Effect of carbon dioxide on oxy-fuel combustion of hydrogen sulfide: An experimental and kinetic modeling

CO2 is an important component in the acid gas and it is necessary to study the effect of CO2 presence on the oxy-fuel combustion of H2S with particular focus on the formation of carbonyl sulfide (COS). The oxy-fuel combustion of acid gas was conducted in a coaxial jet double channel burner. The distribution of flame temperature and products under stoichiometric condition along axial (R = 0.0) and radial at about 3.0 mm (R = 0.75) were analyzed, respectively. The Chemkin-Pro software was used to analyze the rate of production (ROP) for gas products and the reaction pathway of acid gas combustion. Both experimental and simulation results showed that acid gas combustion experienced the H2S chemical decomposition, H2S oxidation and accompanied by H2 oxidation. The CO2 presence reduced the peak flame temperature and triggered the formation of COS in the flame area. COS formation at R = 0.0 was mainly through the reaction of CO2 and CO with sulfur species, whereas at R = 0.75 it was through the reaction of CO with sulfur species. The ROP results indicated that H2 was mainly from H2O decomposition in the H2S oxidation stage, and COS was formed by the reaction of CO2 with H2S. ROP and other detailed analysis further revealed the role of H, OH and SH radicals in each stage of H2S conversion. This study revealed the COS formation mechanisms with CO2 presence in the oxy-fuel combustion of H2S and could offer important insights for pollutant control.

Tunable bidirectional perfect THz absorber realized by graphene-based one-dimensional photonic crystals

In this paper, a perfect absorption structure of graphene-based one-dimensional photonic crystals (1DPC) with tunable absorption channels and absorptivity is proposed. The proposed structure can achieve four perfect absorption peaks with the absorptivity of 99.31%, 99.88%, 99.74% and 99.32% at the same time, and the absorptivity of all absorption peaks is more than 95%. By adjusting the period number of 1DPC, the number of absorption peaks and absorption efficiency can be changed. By changing the chemical potential and relaxation rate of graphene, the absorption of the proposed structure can be dynamically tuned. And the influence of structural layer thickness on absorption property is also explored. In addition, we use this structure to design two different bidirectional absorbers. The designed bidirectional absorber can tailor the perfect absorption frequency with the absorptivity of more than 99.51%, and can change the absorption channel from single channel to double channel and double channel to multi-channel under the forward and backward incidence. This work not only fills the gap in the design of bidirectional perfect absorbers for 1DPC, but also provides a scheme for the design of multifunctional devices.

Design optimization of proton exchange membrane fuel cell bipolar plate

The bipolar plate geometry design is one of the fuel cell's key features that determines the cell's power. It equally has a direct correlation to the thermal and water management of the cell as it tends to regulate the amount of by-product water that can be expunged from the fuel cell. This study, therefore, explored the development of novel bipolar plate geometry designs, namely the square baffled channel, the rectangular baffled channel, the parallel channel design, and the double serpentine geometry design. This was further compared with the traditional serpentine design to ascertain the design with the optimum fuel cell performance. With the squared baffled channel presenting the best results, varying operating conditions that will influence the performance of the novel fuel cell channel design were also evaluated. It was observed that the hydrogen mass fraction increased by 22.6% for the square baffled channel design compared with the other geometry designs considered in the present study. The square baffle channel showed 12.11% increase in power density and 14.54% increase in current density compared to the rectangular baffle channel. In terms of the parallel channel design, the square baffle showed 18.941% increase in power density and 22.278% increase in current density. The least performing channel geometry design was the double serpentine design. Comparing the double serpentine channel geometry design to the square baffle channel geometry design, there was an increase in current density by 67.72% and 77.88% in terms of power density in favour of the square baffle channel geometry design. The square baffle channel also showed 50% increase in current density and 58.23% increase in power density compared to conventional serpentine channel flow plate geometry design. An adaptive neuro fuzzy inference system (ANFIS) was also adopted to predict the output power of the cell. This was then compared with Feed Forward Back Propagation Neural Network to determine the model with the most accurate results. The adaptive neuro-fuzzy inference model accurately predicted the non-linearities associated with fuel cell performance, hence recommended as ideal for Proton Exchange membrane fuel cell prediction. The main contribution for the study is the development of optimal flow plate geometry design that will ensure maximum fuel cell performance. The current study is aimed at providing technical information to policy makers and the fuel cell industry on how optimization of the flow plate design via the introduction of baffles could increase the cell performance hence accelerates its commercialization and widen their applications in various sectors beyond the automotive industry.

Phosphonate-Functionalized Ionic Liquid Gel Polymer Electrolyte with High Safety for Dendrite-Free Lithium Metal Batteries.

The conventional lithium-ion battery technology relies on the liquid carbonate-based electrolyte solution, which causes excessive side reactions, serious risk of electrolyte leakage, high flammability, and significant safety hazards. In this work, phosphonate-functionalized imidazolium ionic liquid (PFIL) is synthesized and used as a gel polymer electrolyte (GPE) to replace the organic carbonate-based electrolyte solution. The as-prepared ionic liquid-based gel polymer electrolyte (IL-GPE) shows low crystallinity, flame retardance, and excellent electrochemical performance. Thanks to the fast double channel transport of lithium ions in the IL-GPE electrolyte, a high ionic conductivity of 0.48 mS cm-1 and a lithium-ion transference number of 0.37 are exhibited. Symmetrical lithium cells with IL-GPE retain stable cycling even after 3000 h under 0.1 mA cm-2. IL-GPE exhibits good compatibility toward lithium metal, yielding excellent long-term electrochemical kinetic stability. IL-GPE induces the formation of a uniform and robust SEI layer, inhibiting the growth of lithium dendrites and improving the rate performance and cycle stability. Furthermore, Li/LiFePO4 cells exhibit a specific capacity of 63 mA h g-1 after 150 cycles at 5.0 C, with a capacity retention of 90.2%. It is foreseen that this GPE is a promising candidate to enhance the safety of high-performance lithium metal batteries.

Heat transfer performance of liquid lead–bismuth eutectic and supercritical carbon dioxide in double D-type straight channel

• The thermal and hydraulic performance for LBE and SCO 2 in PCHE is simulated. • Effects of operational and structural parameters are analyzed in detail. • The heat transfer performance is evaluated based on PEC and GRA. The printed circuit heat exchanger is currently the most recommended heat exchanger type for the lead-bismuth eutectic fast reactor coupled Brayton cycle system. Here, the flow and conjugate heat transfer for lead-bismuth eutectic and supercritical carbon dioxide in a double D-type straight channel printed circuit heat exchanger was investigated using numerical simulations. The results indicated that the overall heat transfer coefficient was positively correlated with the mass flux of both lead-bismuth eutectic and supercritical carbon dioxide, with the latter having a greater effect. Moreover, increasing the temperature difference between the two fluids inhibited the heat transfer effect on the supercritical carbon dioxide side, while increasing the pressure reduced the overall heat transfer coefficient. Further, a reduction in the tube diameter and wall thickness strengthens the overall heat transfer efficiency through enhancing the turbulent kinetic energy of the fluid and reducing the heat transfer thermal resistance, respectively. A performance evaluation criterion and Grey relational analysis were combined to evaluate the heat transfer performance of the printed circuit heat exchanger, and the results showed that a smaller diameter and wall thickness, an increased inlet mass flow rate of supercritical carbon dioxide, and an appropriate reduction in the temperature difference would improve the heat transfer performance.

Topology optimization design of dual-channel metasurface structure with controllable amplitude of retroreflection and mirror reflection

For oblique incident electromagnetic waves, the generation of double reflection channels including retroreflection channel is of great significance in improving target recognition performance and navigation performance. In double channel reflection, controlling the ratio of retroreflection to specular reflection is the key to realizing reflection power distribution. In order to realize the control of the proportion of the reflected power in each channel, a topology optimization method for designing the reflective metasurface microstructure with dual channel is proposed in this paper. The implementation mechanism is investigated, physical model of metasurface with dual reflection channel including retroreflection channel is established, and the topology optimization model of metasurface microstructure with specific power ratio of the retroreflection to specular reflection is established. As a numerical example, a dual channel metasurface reflector with a 1∶1 ratio of retroreflection power to specular reflection power is designed for a 10 GHz plane wave in the TE mode with a pitch angle of –30°. The designed metasurface exhibits strong directionality in the retroreflective direction, and the reflection amplitudes in both directions are similar. The retroreflective metasurface with the maximum retroreflection ratio is designed. The retroreflection ratio of the designed metasurface is 0.093. There is no specular reflection or other singular reflection, and the strong reflection on the metasurface is concentrated at –30°. The ratio of the main beam power to the total reflection power is 0.900. The simulated and experimental results verify the feasibility of the proposed method.

Adaptive modulation methods for combating Doppler shift on correlated double ring channel using FBMC

Adaptive modulation methods for combating Doppler shift on correlated double ring channel using FBMC

A nickel-based metal-organic framework as a new cathode for chloride ion batteries with superior cycling stability.

Chloride ion batteries (CIBs) have drawn growing attention as attractive candidates for large-scale energy storage technology because of their high theoretical energy densities (2500 W h L-1), dendrite-free characteristics and abundance of chloride-containing materials available worldwide. However, the further development of CIBs is greatly limited by sluggish Cl- diffusion and distinct structural variation of cathode materials, resulting in severe decayed capacity and inferior rate performance. Metal-organic framework (MOF) materials possess regular pores/channels and flexible structural designability to accommodate charge carrier ions, but the application of MOFs in anion-type batteries has not been reported. Here, we demonstrate the first example of Ni(dpip) with two different opening sizes of tubular channels serving as the cathode for high performance CIBs. The Ni-based MOF exhibited a stable reversible capacity of 155 mA h g-1 with an admirable low capacity decay of 0.026% per cycle over 500 cycles and superior kinetics with a 10-10 cm2 s-1 average diffusion coefficient for chloride ions as well. The high performance of the Ni(dpip) cathode results from the synergetic redox couples of Ni metal nodes and N-ligands, the unique double-channel structure for reversible Cl-storage, and the low chloride diffusion energy barrier. This work switches on the new application of MOF-based materials as cathodes for CIBs.

Preparation and properties of Al2O3-PF composite functional protective coating on the surface of polymer matrix composites

In this paper, a metal-free ceramic-resin (Al2O3-PF) composite protective coating was prepared on 3240 glass fiber reinforced epoxy resin by high-energy supersonic plasma spraying technology and “double channel and large temperature difference” powder feeding technology. The composite coating not only has good morphology and structure, but also has excellent performance in various properties. It is found that the bond strength of the composite coating can reach 29.60 MPa, and the shear strength can reach 24.24 MPa, far exceeding the research results in related fields at home and abroad. In addition, under the same wear conditions and high temperature ablation, the composite coating can increase the wear resistance and high temperature ablation resistance of the resin matrix by about 2 times, and the insulation resistance of the coating can still reach 2.43 × 1013 Ω after 500 times of high temperature plasma jet ablation, showing excellent insulation performance. However, due to the structural particularity of the composite coating, its erosion resistance and thermal expansion performance need to be further improved.

Improving ECG Classification Performance by Using an Optimized One-Dimensional Residual Network Model

Cardiovascular disease and its consequences on human health have never stopped and even show a trend of appearing in increasingly younger generations. The establishment of an excellent deep learning algorithm model to assist physicians in identifying and the early screening of ECG abnormalities can effectively improve the accuracy of diagnosis. Therefore, in this study, the deep residual network model is adapted for feature extraction and classification of ECG signals by pooling embedded into layers and double channel connection. At the same time, the wavelet adaptive threshold denoising algorithm is used to complete the high signal-to-noise filtering of ECG signals. Then, the alternate pooling residual network (APRN) is compared with the convolutional neural network (CNN), CNN with one residual unit (CNN-R), and the deep residual network (ResNet-18) using ECG datasets from the American MIT-BIH arrhythmia and ST segment abnormality database, European ST-T database, and sudden cardiac death ambulatory ECG database. The results are as follows: The average classification accuracy of the APRN on the four datasets is 97.89%, while the accuracies on CNN, CNN-R, and ResNet-18 are 97.17%, 97.53%, and 97.73%, respectively. In addition, compared with ResNet-18, the classification accuracy of our APRN on each class of data improves by 16.44% in total.

Electrospun Stacked Dual‐Channel Transistors with High Electron Mobility Using a Planar Heterojunction Architecture

AbstractThin‐film transistors based on metal oxide semiconductors have become a mainstream technology for application in driving low‐cost backplanes of active matrix liquid crystal displays. Although significant progress has been made in traditional marketable devices based on physical vapor deposition derived metal oxides, it has still been hindered by low yield and poor compatibility. Fortunately, developing solution‐based 1D nanofiber networks to act as the fundamental building blocks for transistor has proven to be a simpler, higher‐throughput approach. However, oxide transistors based on such princesses suffer from degraded carrier mobility and operational instability, preventing the ability of such devices from replacing present polycrystalline Si technologies. Herein, it is shown that double channel heterojunction transistors with high electron mobility (>40 cm2 V−1 s−1) and operational stability can be achieved from electrospun double channels composed of In2O3 and ZnO layers. Adjusting the stacking order and the stacking density of In2O3 and ZnO layers can effectively optimize the interface electron trap, leading to the formation of 2D electron gas and the reduction of stress‐induced instability. These findings further elucidate the significant advance of electrospinning‐derived double channel heterojunction transistors toward practical applications for future low‐cost and high‐performance electronics.