Polar Plates Research Articles

Influence of low voltage programmed thawing on the quality of frozen pork and its myofibrillar protein

This study explored the effects of low voltage programmed thawing (LVPT) on thawing period, water status, current density as well as physicochemical properties of porcine longissimus dorsi muscle, considering air thawing (AT), water immersion thawing (WT) and cold storage thawing (CST) for the comparison, additionally making fresh meat (FM) as the control. The thawing process used current limiting to gradually reduce the maximum output current to 500, 200 and 100 mA, respectively, by applying a safe voltage of 35 V in a home defrosting apparatus. Using two pairs of foil plate, the thawing (LVPT-2) with dual current loop accelerated the melting of ice crystals than the process with one pair of polar plate (LVPT-1) with one current loop. From −18 °C to −1 °C, the thawing period of LVPT-2 was reduced by 14.54 %, 11.72 %, and 15.95 % compared with that of LVPT-1 for samples within the thickness of 2, 3 and 4 cm, respectively. During the process, the intensity and density of the current loaded on the frozen meat gradually increased. LVPT-1 retained water and reduced its migration inside the meat, and protein solubility was better maintained. As the thickness increased, the effect of LVPT-2 on the moisture distribution and protein solubility of the sample decreased. LVPT-1 treatment resulted in less fat oxidation as well as stable secondary and tertiary structures of myofibrillar proteins compared to other treatments. At low voltage, the ability of LVPT −2 to maintain meat quality was reduced due to the increase in current density. In addition, LVPT-1 reduced muscle damage because of rapid melting of ice crystals. In contrast, LVPT-2 was conductive the formation of hot spots due to dual current loop passed through the pork in final phase of thawing, which would adversely influence the quality of thawed meat. Finally, LVPT could improve the rate of thawing, water binding capacity and meat quality, especially, there was no overheating effect on the meat because of current limiting.

Insulating electromagnetic-shielding silicone compound enables direct potting electronics.

Traditional electromagnetic interference-shielding materials are predominantly electrically conductive, posing short-circuit risks when applied in highly integrated electronics. To overcome this dilemma, we propose a microcapacitor-structure model comprising conductive fillers as polar plates and intermediate polymer as a dielectric layer to develop insulating electromagnetic interference-shielding polymer composites. The electron oscillation in plates and dipole polarization in dielectric layers contribute to the reflection and absorption of electromagnetic waves. Guided by this, the synergistic nonpercolation densification and dielectric enhancement enable our composite to combine high resistivity, shielding performance, and thermal conductivity. Its insulating feature allows for direct potting into the crevices among assembled components to address electromagnetic compatibility and heat-accumulation issues.

Strategies for Reducing the Ohmic Resistance in a Proton Exchange Membrane Electrolysis Cell

Ohmic polarization caused by the contact resistance between components and their own bulk resistance is the main polarization loss in proton exchange membrane electrolysis cells. To investigate this, we adopted an electrolysis cell with an active area of 25 cm2 and explored methods of reducing ohmic resistance. First, two kinds of polar plate were designed to investigate the contact area between transport layer and catalytic layer. The results showed that the polar plate with the higher ridge area made the transport layer and catalytic layer achieve good contact, resulting in an ohmic resistance decreases of 17.5 mΩ cm2 when the contact area increases from 16.85 to 21.6 cm2. Second, Pt coating was used to prevent oxidation of the titanium felt and improve electrolytic performance. Sputtering titanium felt exhibits the best performance with the electrolysis voltage of 1.814 V at 2 A cm−2. Finally, we studied different proton exchange membranes and analyzed the performance and hydrogen permeation rate with the self-made membrane electrode, finding that the electrolytic voltage of the Solvay E98–05 S reaches 1.733 V at 2 A cm−2 due to the minimum thickness and the highest conductivity, and the H2 permeation current density is only 2.184 mA cm−2.

Hydroforming and buckling of a longan-shaped pressure vessel with longitudinal tension rods

ABSTRACT The hydroforming process of a longan-shaped multi-segmented preform with longitudinal tension rods and the buckling behaviour of a hydroformed longan-shaped pressure vessel were numerically and experimentally investigated. The shape of the longan followed the Cassini oval equation, with a shape index of 0.1. A preform with a nominal size of 400 mm for the major axis, 396 mm for the minor axis and a wall thickness of 1 mm was fabricated. Two longitudinal tension rods with a radius of 3 mm and a length of 420 mm were employed in the multi-segmented preform, which was the first to use longitudinal tension rods in the preform. The numerical analysis and experimental results showed that the excessive deformation of the polar plates was significantly reduced. Simultaneously, the overall geometric accuracy of the hydroformed pressure vessel was significantly improved. The results of the analytical, experimental and numerical approaches are in good agreement with one another.

Polarization-sensitive optical coherence tomography for birefringence measurement of calcite nonlinear uniaxial crystal

We report on the new application, to the best of our knowledge, of a time-domain optical coherence tomography (TD-OCT) device used to measure the ordinary n o and extraordinary n e indices of calcite birefringence crystal at room temperature. A 1.25±0.05mm thick slab of calcite crystal is cut, polished, and used as a sample in the OCT arm. While the calcite slab is axially scanned, the raw carrier ordinary signals that came from its front and rear facets are received and denoised with a set of digital filters. The extraordinary signals are generated by the change of beam polarization using a 90°-rotating polarizer plate. It is found that the wavelet transform is capable of reaching the highest signal-to-noise ratio (SNR) of about 24.50 and 23.91 for denoising the ordinary and extraordinary signals, respectively. Quantitative measurement of n o and n e is carried out by extracting a desired envelope from the denoised signals using standard methods. Average values of 1.660 and 1.444 are obtained for n o and n e , respectively, using the wavelet-denoised signals. The weights of the results are finally searched with ones obtained from two sets of dispersion equations. We found a very good agreement between the wavelet-denoised OCT- and dispersion equation-based values with a very low relative differences of 0.04% and 2.8% for n o and n e , respectively, when the Ghosh equation is used and averaged ones of 1.3% and 4.2% for n o and n e , respectively, when the Zhao et al. equation is applied.

Three-Dimensional Electrochemical Oxidation System with RuO2-IrO2/Ti as the Anode for Ammonia Wastewater Treatment

In this study, a three-dimensional electrochemical oxidation system was constructed to treat ammonia nitrogen wastewater generated from the tail gas absorption of a methionine producer by using a homemade MAC mixed with a GAC at a mass ratio of 1:2 as the particle electrode, with a RuO2-IrO2/Ti polar plate as the anode and a stainless steel plate as the cathode. The effects of current density, initial pH value of wastewater, plate spacing, NaCl concentration and particle filling amount on CODCr and NH4+-N removal were investigated through single-factor experiments, and the removal pathways of CODCr and NH4+-N under the system were initially explored via cyclic voltammetry curves, scanning electron microscopy and tertiary butanol quenching experiments. The experimental results showed that the average removal rate of CODCr was 91.03% and that of NH4+-N was 98.89% after electrolysis for 5 h under the conditions of a current density of 40 mA/cm2, no pH adjustment, the spacing of the electrode plates of 8 cm, the NaCl dosing concentration of 1 g/L, and the particle filling amount of 400 g/L. Under this experimental condition, the removal of CODCr occurred mainly through the indirect oxidation of active chlorine and ·OH, and the removal of NH4+-N mainly through the indirect oxidation of active chlorine.

Structure optimisation of cathode parallel polar plate PEMFC based on topology optimisation

Polar plate design can directly affect the performance of the proton exchange membrane fuel cell(PEMFC). A novel topology parallel polar plate design is proposed to improve cell performance. We used the sparse nonlinear optimisation (SNOPT) algorithm to freely evolve the 2D model and obtain the output material factor distribution map. While keeping the height of the gas diffusion layer constant, the channel height is stretched proportionally to the output material factor to obtain 3D models. By analyzing the mass transfer, water management, and cell performance, the results indicate that increasing the selection range of material output factors is beneficial for the diffusion of reactive gases, reducing pressure loss, and improving cell performance. Reducing the selection range of material output factors helps increase the reaction gas flow rate and enhancing drainage performance. The optimisation model with lower limits benefits oxygen diffusion, increasing gas flow rate and pressure loss, and has little impact on drainage. Case 6 performs well in mass transfer and drainage performance, and the pressure loss is relatively small. The quantitative evaluation shows that Case 6 has an improvement of 22.2% compared to the parallel polar plate and 26.5% compared to the serpentine polar plate in cell efficiency.

Сравнение двух типов подвижных фаз для определения витаминов группы В методом тонкослойной хроматографии

Thin-layer chromatography (TLC) has been used to study the influence of a number of factors (the nature of the stationary phase, the nature and concentration of the organic solvents and surfactants, the pH of the buffer solution) on the chromatographic characteristics of B vitamins: B 1 (thiamine), B6 (pyridoxine), B12 (cyanocobalamin). The stationary phases were plates with polar (Sorbfil on a polymer (highperformance plates, HTLC) and aluminum substrates), weakly polar (Polyamide-6), and nonpolar (RP-18 on an aluminum substrate) sorbents. As micellar mobile phases – micellar solutions of cetylpyridinium chloride in the concentration range 5–10-4 – 5–10-1 M, sodium dodecyl sulfate in the concentration range 2,5–10-4 – 5–10-1 М. It has been established that among aqueous-organic mobile phases (MF) the best results have been obtained for MF of the composition acetonitrile – water (15:385) on polar high-performance plates. More effective than acetonitrile – water is the PF of the composition acetonitrile – cetylpyridinium chloride (15:85) in the presence of a phosphate buffer solution with pH = 3. For the last PF, TLC determination of vitamins B1, B6, B12 in pharmaceutical preparations with a Sr value of interval 0.01–0.06 has been developed.

Development of novel single fuel cell based on composite polar plates for highly efficient power generation

In proton exchange membrane fuel cells (PEMFCs), bipolar plate (BPP) and membrane electrode assembly (MEA) are arranged alternately to construct a fuel cell stack for power generation. This construction method may affect the power generation performance of fuel cell stack or even damage the MEA components. To improve the fuel cell stack's assembly efficiency, we propose a novel single fuel cell that consists of two composite polar plates and a MEA, the composite polar plate is formed by a nylon frame and a titanium thin sheet with microchannels. The structural design of the single cell and its working principles are firstly presented, and followed by the fabrication of the single fuel cell. A three dimensional (3D) numerical model is developed to investigate the internal electrochemical reaction behaviors of the single fuel cell. Then, experimental tests are conducted to test its electrochemical performance for power generation. The obtained results showed that the open circuit voltage can reach 0.93 V and energy density is approximately 813.83 mW/cm3, indicating our developed single fuel cell had a high energy utilization efficiency for power generation. Therefore, our developed single fuel cell has the potential to power unmanned aerial vehicles (UAVs), robotics, and new energy vehicles.

Optical properties of the dual circularly polarized lights reflected from ITO films under electric and thermal fields.

Indium tin oxide (ITO) is widely used in optoelectronic devices due to its excellent optical and electrical properties. The real-time characterization of the ITO surface under electric and thermal fields plays an important role in determining its performance. The Goos-Hänchen (GH) and Imbert-Fedorov (IF) shifts and polarization properties of the dual circularly polarized lights reflected from ITO films can be used to describe its features. The dual circularly polarized lights, right circularly polarized (RCP, S 3≈+1) and left circularly polarized (LCP, S 3≈-1) lights, are obtained by rotating the linear polarizer and quarter-wave plate. The polarization properties and the lateral shifts of the RCP and LCP lights were studied by a polarimeter and a slim beam profiler. The results show that the polarization properties of the dual circularly polarized lights are mainly affected by temperature. The degree of the polarization properties of the RCP and LCP lights changed from 97.85% to 97.40%, and from 98.40 % to 83.50%, respectively. The reflectivity of the RCP and LCP lights changed from 42.19% to 40.37%, and from 43.80% to 0.80%, respectively. The GH and IF shifts of the RCP light are 156.50µm and186.00µm, respectively. The GH and IF shifts of the LCP light are 233.00µm and 257.00µm, respectively. The ITO film has more effect on the LCP light than that of the RCP light due to its strong ITO film (400) plane.

A Kalman Filter-based Method for Measuring the Spacing of Tiny Parallel Capacitor Plates

The method uses multivibrators composed of the 555 timer as the Tiny Polar Plate Pitch Capacitive Sensor, and programs the MCU to construct a discrete Kalman filter to filter the capacitance data, and then uses the arithmetic averaging method to obtain the fluctuating capacitance values at a fixed parallel plate pitch. Then, we use the capacitance data for “state estimation.” We first update the estimate of the state variable using the estimated real data of the previous moment and the observed real data of the current moment, and then predict the real parallel plate pitch for the next moment. Multiple measurements give enough data, which are very close to the real results using the Kalman filter [1]. After extensive experimental measurements, this method can achieve 99% accuracy within 0 mm to 5 mm.

Investigation of load-bearing capacity of rigid-plastic reinforced ellipsoidal shells of rotation

For ellipsoidal fiber-reinforced shells of rotation, the upper (kinematic) limit of load-bearing capacity is determined. The structures are clamped along the lower support contour and have rigid polar plate. The material of the components is rigid-plastic with asymmetry in tension and compression. The matrix is orthotropic. The principal axes of matrix anisotropy coincide with meridional, circumferential and transverse directions. Two-layer shell model and refined relations of structural model with two-dimensional stress state in components are used. Extreme problem is formulated and numerically solved for spherical and two different ellipsoidal shells. Influence of reinforcement parameters on limit load is investigated.

Perfect Narrow‐Band Absorber of Monolayer Borophene in All‐Dielectric Grating Based on Quasi‐Bound State in the Continuum

AbstractBorophene has the unique optical properties of two‐dimensional materials and its own anisotropic characteristics. This work proposes a perfect narrow‐band absorption structure to enhance the interaction of light with the monolayer borophene inserted into two different dielectric gratings. The structure efficiently improves absorption efficiency based on the quasi‐bound states in the continuum (Q‐BIC). The absorption characteristics are numerically simulated and theoretically analyzed by using the rigorous coupled‐wave analysis (RCWA) method and the finite element method (FEM). The absorption efficiency of the monolayer borophene is high, up to 99.18% with a full‐width at half maximum (FWHW) of 0.62 nm, achieving nearly perfect narrow‐band absorption. Moreover, the mechanism of enhanced absorption of monolayer borophene is verified by the coupled mode theory (CMT), which indicates that the nearly perfect absorption is also derived from the critical coupling. At the same time, the influence of the thickness and width of the two layer dielectric structure on the absorption efficiency is theoretically analyzed. Furthermore, due to the anisotropic optical properties of the structure for TE and TM polarized light, a narrow‐band polarization plate or sensor can be realized. The structure designed provides a new possibility to enhance the interaction between monolayer borophene and light.

Preliminary thermal hydraulic analyses on electrostatic residual ion dump for CRAFT NNBI

Neutral beam injection is an important auxiliary heating and current driving method for magnetic confinement fusion research. In order to better build the Neutral Beam Injector with Negative Ion Source (NNBI), the pre-research on key technologies has been carried out for the Comprehensive Research Facility for Fusion Technology (CRAFT). Combined with the theoretical design, the maximum heat deposition distribution on the surface of the polar plate in the case of normal operation is analyzed. Then, according to the actual heating load on the surface of the polar plate, the heat removal simulation under the optimized beam power distribution is carried out. The improvement of the heat transfer performance of the water-cooled structure by the spoiler structure is simulated. The results show that the water-cooled structure of the electrostatic residual ion dump can meet the heat removal requirements of the system.

Engineering and Resource Science Education on the Investigation of the Activation Method of Formation Water

A purpose of the engineering and resource science education is to bring up human resources of effective utilizing natural resources, considering environmental conservation for making sustainable society. As seen in the description of the course of study, the promotion of ESD is regarded as important in elementary and secondary education. Japan ranks second, after Chile, in the production of iodine in the world, and formation water in Minami-Kanto gas fields is the biggest supply source in Japan. The formation water can be substantially used for science education. However, the activation method of the formation water has not been well investigated. In this study, we developed the following teaching materials using the formation water in Minami-Kanto gas fields:1) extraction of iodine from the formation water and 2) making polarizing plates using the extracted iodine. We found that 18 L of the formation water was required to perform two experiments for one class: preliminary experiments and educational practice for university students. The teaching material developed has the potential to create interest in students not only in science experiments but also in engineering and resource science.

Design for the reconfigurable polarization rotator by inhibiting Fano resonance with graphene-metal grating structures

In this paper, the Fano resonance associated with the integrated grating-enhanced transmissive cross-polarization rotator (TCPR) superimposed via two polarization plates operating in disparate frequency bands is observed. The metal resonance frequency dramatically impacts the Fano effect, which triggers alterations in polarization conversion ratio (PCR). Through the analysis for the surface current distributions, the spring vibrator model driven by external forces in two orthogonal directions is employed to figure out the internal mechanism of the Fano line shape in the PCR curve. Subsequently, the symmetrical lateral current branches on the two gold polarization sheets are accessible. The relative bandwidth (RBW) value and the operating region of the ultimate optimized TCPR are 84.6% and 0.563 THz–1.388 THz, respectively. In other words, the PCR band is expanded successfully. Intended to obtain the fabulous polarization switching behavior to enhance the reconfigurability, the gated voltagedriven graphene is doped in grating gaps with the chemical potential fluctuating uniformly between 0.01 and 0.50 eV. The proposed optimizations with the PCR and the final TCPR are distinguished from precedented instances in the RBW and tunability, which is universally applicable in multitudinous terahertz-controlled scenarios.

Holistic and efficient calibration method for Mueller matrix imaging polarimeter with a high numerical aperture.

High-numerical aperture (N A>0.6) Mueller matrix imaging polarimeter (MMIP) (high-NA MMIP) is urgently needed for higher resolution. Usually, the working distance of high-NA MMIP is too short to perform in situ calibration by a usual reference sample, such as polarizer and retarder plates. The polarization effects of the substrate that attach the sample are never calibrated. So, the resolution and accuracy of the MMIP is hard to further promote. In this paper, a holistic and efficient calibration method is innovated for high-NA MMIP. Two film polarizers and a film retarder as well as a blank substrate are first adopted as the reference samples in calibration. Different from the conventional eigenvalue calibration method (ECM), the holistic calibration theory and process are established. All polarimetric errors arising from the devices, subsystems, and the substrate can be calibrated in one process. The normalized measurement error is less than 0.0024 for NA 0.95 MMIP, which is an order of magnitude lower than those of NA 0.1 and 0.2 MMIPs in publications. The excellent performance of calibrated high-NA MMIP is demonstrated by tissue polarimetry with higher resolution, accuracy, and more appropriate dynamic range.

Optimization and design for additive manufacturing of a fuel cell end plate

Proton exchange membrane fuel cells (PEMFCs) represent today one of the most common types of fuel cells for mobility applications due to their comparatively high-power density, low operating temperature, and low costs. A PEMFC regularly consists of a stack of individual cells in which each consists of polar plates and a membrane electrode assembly. To achieve the best possible electric conductivity over the series connection of cells, the contact pressure in between the cells must be uniformly distributed over the cell area. This pressure is usually applied to the stack by end plates, which frame the stack and are clamped together by bolts, which are tightened by a defined torque. Typically, these end plates are made from bulk material with no or limited optimization. Looking at mobility applications, e.g., in aerospace, a fuel cell should ideally provide high efficiency at the lowest weight. Based on this assumption, this paper uses topology optimization varying the material as well as the design space to derive new design concepts for the end plates of a PEMFC. The designs are compared with respect to an even stress distribution to the fuel cell stack, the weight of the plates, and the manufacturability in the laser powder bed fusion process. The most promising design is manufactured and results in a weight decrease of 48% compared to previously used aluminum bulk plates. Finally, the optimized base plates are applied to a test cell and the performance is compared to their conventional counterparts, showing a 1% increase in electric stack power despite the lower mass.

Resonators with a continuously variable output coupling rate to enhance output performance of Yb:YAG thin-disk lasers.

Beam quality and average output power are two long-sought parameters of continuous-wave lasers. The operating characteristics of a Yb:YAG thin-disk laser based on a 72-pass pump module using output couplers with continuously variable coupling rates are reported. When the pump power is 450 W, the average power of more than 210 W is obtained, and the corresponding optical-optical efficiency is about 46.67%. The output beam is near diffraction limited with M2=1.20 and 1.18 on the horizontal and vertical directions respectively. The thin-disk laser maintains the beam quality near diffraction limited within the whole pump power range by continuously changing the coupling rate of the output coupler (the combination of thin film polarizer and quarter-wave plate) according to the incident pump power. The experimental results show that by continuously changing the coupling rate, combined with the dynamic change of thermal lens effect, the laser beam quality factor M2 can be reduced from 2.0 to 1.2, and the beam quality can be improved by about 40%. The improvement of and increase of average output power confirm that resonators with continuously variable coupling rate are a promising method for enhancing output performance of thin-disk lasers.

Formation of high-order cylindrical vector beams with sector sandwich structures

Complex polarization-phase transformations are considered, which are implemented using easy-to-manufacture optical elements. The manufacturing technology of such elements is based on the axially symmetric discretization of the required polarization and phase distributions. This representation leads to optical elements in the form of sector sandwich structures consisting of polarizing and phase plates stacked together. The paper numerically and experimentally investigates the main types of such sector sandwich structures for the formation of second-order cylindrical polarizations.