Non-uniform Structure Research Articles

The sedimentation probability model based on the particle size distribution and cake morphology in the cross-flow membrane process

Evolution of non-uniform cake structure in the cross-flow membrane process was investigated in this study. Considering the real cake surface morphology and particle size distribution, the sedimentation probability of foulant (γ) was calculated, then a new flux prediction model based on the mass conservation on the cake surface was proposed. Results showed that the predictions of the new model had excellent agreements with experimental data (R2 > 0.97), wherein cake surface heights obeyed normal distribution and protrusion heights approximately obeyed exponential distribution. Meanwhile, γ decreased with cross-flow velocity from 4.59 % (0.24 m/s) to 2.53 % (0.48 m/s), whereas γ increased with trans-membrane pressure from 2.80 % (0.1 MPa) to 6.44 % (0.2 MPa). In addition, a skin layer which was approximately about 20 % of total cake thickness but possessed 70 % of the total resistance, was also observed in the cross-flow mode. These results provided a brand-new perspective (tuning cake morphology or structure) on the essence of membrane fouling alleviation.

Anatomy of the distal tendinous structure of the triceps brachii: implications for the role of the triceps brachii to resist valgus elbow forces during baseball pitching.

Biomechanical studies suggest that the triceps brachii muscle generates resistive force against valgus stress on the elbow during baseball pitching. However, given the parallel fiber orientation in the distal tendinous structure of the triceps brachii, the mechanism behind this anti-valgus force remains unclear. In the present study, we aimed to examine the anatomy of the distal tendinous structure of the triceps brachii using bony morphological, macroscopic, and histological methods. We analyzed 25 elbow specimens from 18 cadavers, all of Japanese ethnicity, using micro-computed tomography (micro-CT). Four specimens were excluded due to severe osteophytes, leaving 21 specimens randomly allocated to three groups: 13, 4, and 4 specimens to the macroscopic examination group, the histological examination group, and the chemically débrided bone examination group, respectively. In 6 of the 13 specimens analyzed macroscopically, we quantitatively measured the local thickness of the triceps tendon using micro-CT. The distal tendinous portion of the triceps brachii was comprised of an intramuscular tendon and a superficial aponeurosis. The intramuscular tendon, located between the long and medial heads of the triceps, curved medially to laterally and inserted broadly onto the proximal and lateral facets via fibrocartilage. The superficial aponeurosis, attached to the lateral and medial heads, had fibers that ran straight and merged distally with the aponeurosis of the anconeus. The intramuscular tendon (2.2 ± 0.4 mm) was significantly thicker than the superficial aponeurosis (0.9 ± 0.2 mm, P < 0.001). The current study revealed a nonuniform distal tendinous structure of the triceps brachii, with a thick intramuscular tendon and a thin superficial aponeurosis. In particular, the intramuscular tendon was curved from the medial-to-lateral direction and had a firm insertion. These findings suggest that the intramuscular tendon can contribute force to prevent valgus stress on the elbow as a dynamic stabilizer during the pitching motion.

Study on spectral characterization of non-uniform PT symmetry Bragg gratings with duty-cycle modulation

Abstract It is a great challenge to improve the detection efficiency of optical structures. In order to increase the reflection effect of Bragg grating, a non-uniform PT-symmetric Bragg grating structure based on duty cycle modulation is proposed. The grating exhibits PT symmetry by quantum doping technology and is optimized by analyzing the structural parameters which have great influence on the grating. Two methods of Odd-function Duty-cycle Modulation (ODC) and Even-function Duty-cycle Modulation (EDC) are proposed to obtain the non-uniform grating structure under duty cycle modulation. The results show that the reflectivity of the grating is obviously enhanced under odd-function duty cycle modulation. Our method improves the reflection characteristics of the Bragg grating to a great extent, and is conducive to designing more efficient reflectivity detection devices.

Non-Radical Mediated Photocatalytic H2O2 Synthesis in Conjugate-Enhanced Phenolic Resins with Ultrafast Charge Separation.

It is essential for the development of highly efficient polymeric photocatalysts for hydrogen peroxide (H2O2) production. Nevertheless, the non-uniform molecular structures and sluggish reaction pathway of polymeric photocatalysts lead to low conversion efficiency. In this work, we report sulfur-contained phenolic resins with regulated conjugation for photocatalytic H2O2 production. Due to the substitution of sulfur for methylene in the phenolic resin structure, the conjugation degree of the material is adjusted, resulting in the formation of a built-in electric field. This effectively enhances the charge separation capability, enabling charge carriers to react faster with substrates. Through in-situ characterization and theoretical calculations, we have unveiled that the introduction of sulfur can modulate the reaction pathway of phenolic resin materials, enabling a dual-pathway photocatalytic H2O2 production mediated by non-radical species. Impressively, the sulfur-contained resin photocatalyst showcases exceptional H2O2 production activity with a solar-to-chemical conversion efficiency of 1.4% exceeding most reported systems, and generates 25 mmol m-2 of H2O2 under natural sunlight through large-scale equipment. This work provides a facile strategy to separate the photogenerated electron-hole pairs of polymer photocatalysts to achieve efficient artificial photosynthesis.

Radially polarized partially coherent beams with prescribed sinh-Gauss non-uniform correlation structure

We introduce a kind of radially polarized partially coherent beam with a prescribed sinh-Gauss non-uniform correlation structure, named a radially polarized sinh-Gauss non-uniformly correlated (RPSNC) beam. Utilizing the ordinary Huygens–Fresnel principle, we derive the analytical formulas for the spectral intensity and the spectral degree of polarization (DOP) in free space and investigate the beam’s propagation properties through numerical simulations. The results demonstrate that RPSNC beams exhibit a self-focusing property during propagation, with the focal position adjustable by varying the coherence length. Additionally, the spectral DOP in the central region forms a distinctive single-ring structure as the beam propagates. These unique properties make RPSNC beams promising for applications in free-space optical communications, beam shaping, and optical trapping.

A Hybrid Analytical Model of Open-Circuit Air Gap Magnetic Field of Interior Permanent Magnet Synchronous Motor With Non-Uniform Air Gap Structure Considering Saturation Effect

A Hybrid Analytical Model of Open-Circuit Air Gap Magnetic Field of Interior Permanent Magnet Synchronous Motor With Non-Uniform Air Gap Structure Considering Saturation Effect

The GMI effect of Fe-based microwires with a partially crystallized near-surface layer

The GMI effect was investigated in microwires based on a Fe70Si18B9Cu1Nb2 alloy (ρ = d/D = 0.5, d = 15 µm) after heat treatment at 550 °C resulting in the formation of a non-uniform nanocrystalline structure. It was shown experimentally that short heat treatments (≤2 min 40 s) led to the emergence of α-Fe(Si) nanocrystals near the surface of a microwire while the central part of the microwire remained amorphous. Simultaneous processes of stress relaxation and formation of the nanocrystalline structure induced an enhancement of the GMI effect. A maximum value of ΔZ/Z = 150 % was observed at a frequency of 200 MHz. With an increase in the heat treatment time, the soft magnetic properties of the surface layer degenerated, resulting in the degradation of the observed GMI effect.

Uncovering the structure and kinematics of the ionized core of M 2-9 with ALMA

We present interferometric observations at 1 and 3 mm with the Atacama Large Millimeter Array (ALMA) of the free-free continuum and millimeter(mm)-wavelength recombination line (mRRL) emission of the ionized core (within ≲130 au) of the young planetary nebula (PN) candidate M 2-9. These inner regions are concealed in the vast majority of similar objects. A spectral index for the mm-to-centimeter(cm) continuum of ~0.9 indicates predominantly free-free emission from an ionized wind, with a minor contribution from warm dust. The mm continuum emission in M 2-9 reveals an elongated structure along the main symmetry axis of the large-scale bipolar nebula with a C-shaped curvature surrounded by a broad-waisted component. This structure is consistent with an ionized, bent jet and a perpendicular compact dusty disk. The presence of a compact equatorial disk (of radius ~50 au) is also supported by redshifted CO and 13CO absorption profiles observed from the base of the receding northern lobe against the compact background continuum. The redshift observed in the CO absorption profiles likely signifies gas infall movements from the disk toward a central source. The mRRLs exhibit velocity gradients along the axis, implying systematic expansion in the C-shaped bipolar outflow. The highest expansion velocities (~80 km s−1) are found in two diagonally opposed compact regions along the axis, referred to as the high-velocity spots or shells (HVSs), indicating either rapid wind acceleration or shocks at radial distances of ~0.″02–0.″04 (~ 15–25 au) from the center. A subtle velocity gradient perpendicular to the lobes is also found, suggesting rotation. Our ALMA observations detect increased brightness and broadness in the mRRLs compared to previously observed profiles, implying variations in wind kinematics and physical conditions on timescales of less than two years, which is in agreement with the extremely short kinematic ages (≲0.5–1 yr) derived from observed velocity gradients in the compact ionized wind. Radiative transfer modeling indicates an average electron temperature of ~15 000 K and reveals a nonuniform density structure within the ionized wind, with electron densities ranging from ne≈106 to 108 cm−3. These results potentially reflect a complex bipolar structure resulting from the interaction of a tenuous companion-launched jet and the dense wind of the primary star.

Numerical simulation of battery thermal management based on ring microchannel cold plate

Efficient heat dissipation methods have been the focus of battery thermal management research. Due to the limitations of flow and heat transfer in traditional straight channel cold plates (SCCP), this paper introduces a ring channel cold plate (RCCP) and utilizes the j/f factor to evaluate the comprehensive thermal performance of the cold plates. Through comparison and analysis, it is found that the RCCP has a lower pressure drop and better comprehensive thermal performance. As the mass flow rate increases, the j/f improvement effect of the RCCP becomes more pronounced. Additionally, when the branch channel width is 6 mm, the RCCP exhibits higher comprehensive thermal performance. However, in the RCCP of equal width, the innermost channels have the shortest flow path and the largest flow rate. To further enhance heat transfer, the influence of non-uniform structure on the performance of RCCP is investigated. The result shows that the narrow inside and wide outside channel arrangement can enhance the heat transfer performance of the RCCP but at the cost of increasing pressure drop. Among them, the outermost, middle, and innermost channel widths of 6.66 mm, 6 mm, and 4 mm, the cold plate has better comprehensive thermal performance, more suitable for battery thermal management. The RCCP with a narrow inside and wide outside provides a new option for more efficient battery thermal management.

Single motor driven soft actuator design based on nonuniform sheering auxetic structure

Abstract Grasping functionality is one of the core functionalities that a manipulator needs to possess. Traditional rigid manipulators are typically composed of rigid materials. However, when dealing with objects of complex shapes, irregular surfaces, or soft materials, rigid manipulators often face challenges in effectively grasping and stably holding objects due to their rigidity, which can lead to damage or failure. To address these issues, constructing manipulators using soft actuators can be highly advantageous. In most current research, soft actuators are typically composed of flexible materials and fluids, which can result in highly complex dynamic behaviors and nonlinear characteristics. This complexity makes precise modeling and control of soft actuators more challenging, necessitating the use of advanced control algorithms and techniques to mitigate nonlinear effects. In this study, we first establish a mathematical model for the torsional and bending deformations of non-uniform shearing-auxetic structures. Subsequently, we validate the reliability of the mathematical model through simulation. Finally, we design a soft actuator that requires only single-motor control, which is based on the structural design of non-uniform shearing-auxetic structures. This type of soft actuator not only simplifies control aspects but also facilitates practical modeling and manufacturing processes. Moreover, it’s capable of achieving spiral grasping functionality.

Metal–Organic Framework Monoliths for Lithium Metal Batteries with Long Cycle Lifetimes

Lithium metal with low electrochemical potential and high theoretical capacity has attracted significant attention as an anode material for high-energy-density batteries. However, the practical application of Li metal anodes has been inhibited by the growth of Li dendrites during charge–discharge cycling. Nano- or micro-porous layers have been introduced at the Li/electrolyte interface to regulate the Li+ flux and stabilize the Li metal anode. However, such interlayers fabricated via slurry-casting have non-uniform porous structures containing interparticle voids due to the binders and solvents, which reduces the efficacy of the interlayer in suppressing dendritic Li growth. Herein, we report mechanically robust void-free metal–organic framework (MOF) monoliths that can effectively homogenize the Li+ flux and suppress dendritic growth. MOF monoliths (500 nm-thick) are directly grown on a polypropylene separator without binders via a simple chemical route with a void-free structure and mechanical robustness (Young’s modulus of ~7.8 GPa). The monolithic MOF film facilitates the filtration of large anions through the nanopores, resulting in an increased Li+ transference number. Furthermore, electrochemical simulations and experiments confirm that MOF monoliths with well-ordered nanopores but without interparticle voids effectively redistribute the locally concentrated Li+ flux over the Li anode, leading to reversible Li plating and stripping. A Li metal battery (full cell) with MOF monoliths operates stably over 300 cycles with a capacity retention of 96.6%. The interlayer design proposed in this study offers the possibility of commercializing high-energy-density Li metal batteries with long cycle lifetimes.

Robust, High-Temperature-Resistant Polyimide Separators with Vertically Aligned Uniform Nanochannels for High-Performance Lithium-Ion Batteries.

Separator is an essential component of lithium-ion batteries (LIBs), playing a pivotal role in battery safety and electrochemical performance. However, conventional polyolefin separators suffer from poor thermal stability and nonuniform pore structures, hindering their effectiveness in preventing thermal shrinkage and inhibiting lithium (Li) dendrites. Herein, we present a robust, high-temperature-resistant polyimide (PI) separator with vertically aligned uniform nanochannels, fabricated via ion track-etching technology. The resultant PI track-etched membranes (PITEMs) effectively homogenize Li-ion distribution, demonstrating enhanced ionic conductivity (0.57 mS cm-1) and a high Li+ transfer number (0.61). PITEMs significantly prolong the cycle life of Li/Li cells to 1200 h at 3 mA cm-2. For Li/LiFePO4 cells, this approach enables a specific capacity of 143 mAh g-1 and retains 83.88% capacity after 300 cycles at room temperature. At 80 °C, the capacity retention remains at 85.92% after 200 cycles. Additionally, graphite/LiFePO4 pouch cells with PITEMs display enhanced cycling stability, retaining 73.25% capacity after 1000 cycles at room temperature and 78.41% after 100 cycles at 80 °C. Finally, PITEMs-based pouch cells can operate at 150 °C. This separator not only addresses the limitations of traditional separators, but also holds promise for mass production via roll-to-roll methods. We expect this work to offer insights into designing and manufacturing of functional separators for high-safety LIBs.

Microstructure and mechanical properties of laminated Ti-TiBw/Ti composites fabricated by wire arc additive manufacturing

To achieve the synergetic improvement of the strength and ductility of titanium matrix composites (TMCs), in this study, flux-cored wires were customized and combined with the wire arc additive manufacturing (WAAM) process to fabricate laminated Ti-TiBw/Ti composites. The diffusion behavior of the reinforcement during the WAAM deposition process was studied in detail. By optimizing the process parameters to regulate the distribution of the reinforcement, the composites presented a laminated structure on the macroscale and a non-uniform distributed network structure on the microscale. Compared with pure titanium, the ultimate tensile strengths and ductility of the laminated Ti-TiBw/Ti composites have both improved. The ultimate tensile strengths of the composites with 5 vol% and 10 vol% TiBw/Ti layers are 574 MPa and 663 MPa, respectively, and the fracture elongation are 27.74 % and 24.95 %, respectively. This heterogeneous structure of TMCs reconciles the contradiction between strength and ductility, mainly attributed to the strengthening effect of in-situ synthesized TiBw and the toughening effect of the laminated structure and the TiBw network structure.

Inversion for Equivalent Electromagnetic Parameters of Nonuniform Honeycomb Structures Based on BP Neural Network

Inversion for Equivalent Electromagnetic Parameters of Nonuniform Honeycomb Structures Based on BP Neural Network

Experimental Simulation Studies on Non-Uniform Fluidization Characteristics of Two-Component Particles in a Bubbling Fluidized Bed

Taking the fluidized pre-reduction process of iron ore powder bubbling fluidized bed as the background, for the problem of non-uniform structure in the bed of gas-solid fluidization process, the non-uniform fluidization characteristics of bicomponent particles are investigated in a cold two-dimensional bubbling fluidized bed by using a combination of physical experiments and mathematical simulations. Fluidization experiments were carried out under typical working conditions by using glass beads to study the effects of apparent gas velocity, mass ratio, and other factors on the non-uniform structure in the bed. Through the experimental observation of the bubble behavior, the effect of the cyclic change in bubble formation, rise and growth to rupture on the bed uniformity were analyzed. The experiments showed that the fluidized bed of two-component particles would be stratified, and the non-uniformity was strong in the upper part and weak in the lower part, and the apparent gas velocity and particle size were the main influencing factors. Based on the Euler-Lagrange reference frame modeling, the fluidization process of the two-dimensional bubble bed was simulated by the CFD-DEM method. The simulations of typical experimental conditions were carried out to further analyze the velocity distribution and the volume ratio of each phase in the bed from the gas-solid interaction level, revealing that the velocity distribution in the upper part of the bed is not uniform, and the gas flow is strongly perturbed, with intense bubble aggregation. The results reveal the reasons for the non-uniform phenomenon of gas-solid fluidization, which can provide a theoretical basis for the regulation of the non-uniform structure of the fluidization process.

Electrodeposition of Thin Film Cu-Zn-Sn Alloy for Water Splitting Application

An energy transition to renewable energy sources is necessary due to the scarcity of fossil fuels and their detrimental effects on the environment. Water splitting process is one of the practical and effective way that does not occur spontaneously. This study investigates catalytic activity of Cu-Zn-Sn (CZT) photocatalyst in hydrogen evolution and oxygen evolution reaction. The CZT deposited with varied electrolyte’s pH of 6 and 9 on indium tin oxide substrate at the room temperature for 600 seconds. According to the X-ray diffraction patterns, there were Cu6Sn5, Cu5Zn8, and Sn metal phases with monoclinic, cubic, and cubic crystal systems. The scanning electron microscopy technique results of all CZT alloy sample showed a dense, non-uniform, and polycrystalline surface structure. The CZT alloys were found to have an average particle size of 0.35 μm. CZT alloys can produce a photocurrent density of 0.19 mA/cm² at a potential of 1.29 V vs RHE. the charge transfer resistance of CZT synthesized at pH 6 is lower (21.48 Ω) compared to pH 9 (28.36 Ω). The Tafel slope of HER for pH 9 CZT was -133 mV/dec, which was lower than that of pH 6 CZT (-88 mV/dec), indicating faster H2 production and corrosion resistance on pH 9 CZT.

Development of mathematical models of heat conductivity for modern electronic devices with elements containing foreign inclusions

This paper considers the heat conduction process for an isotropic medium containing a foreign half-through inclusion and heated by a locally concentrated heat flow. Linear and non-linear mathematical models for determining the temperature field have been built to establish the temperature regimes for the effective operation of electronic devices. The coefficient of thermal conductivity of a non-uniform structure is represented as a whole, using asymmetric unit functions, which automatically provides the conditions of ideal thermal contact on the surfaces of materials. This results in solving one heat conduction equation with discontinuous and singular coefficients. A linearizing function was introduced to linearize the nonlinear boundary value problem. Analytical-numerical solutions of linear and nonlinear boundary-value problems have been obtained in a closed form. A linear temperature dependence of the coefficient of thermal conductivity of structural materials was chosen for a heat-sensitive medium. As a result, an analytical-numerical solution was derived, which determines the temperature distribution in this medium. On this basis, a numerical experiment was performed, the results of which are graphically displayed and confirm the adequacy of the constructed mathematical models to a real physical process. The materials of the plate and inclusion are silicon and silver. The results for these materials based on the linear and non-linear model differ by 7 %. Their slight difference is explained by the fact that the values of the temperature coefficient of thermal conductivity are small. The models built make it possible to analyze the given environments in terms of their thermal resistance. As a result, it becomes possible to improve it, and protect structures from overheating, which could lead to the failure of individual nodes and their elements and the entire electronic device

Numerical simulation of non-uniform solidified structure growth of continuous casting slab based on cellular automaton finite-element model

ABSTRACT A coupled cellular automaton-finite element model was created to simulate solidification structure growth, which was validated experimentally. Simulations were conducted to examine the temperature distribution and growth of the solidification structure during the initial phase within the mold. Temperatures were measured in four key regions: the wide face center, narrow face center, corner, and hot spot. The growth of the solidification structure in these regions was also simulated. The results revealed uneven solidification areas, temperature distribution, and grain size during the e-arly stages of solidification in the mold. The continuous casting slab's corner showed a thicker shell compared to the wide and narrow face centers, with the shell being thinnest at the hot spot. The lowest temperature was found at the corner, and the highest at the hot spot, leading to a highly uneven temperature distribution near the corner. Grain size was smallest at the corner and largest at the hot spot. To enhance the quality of the continuous casting slab, particular attention must be given to the uneven grain size, temperature, and shell thickness near the hot spot, which are influenced by deviations at the corner.

Effect of short-time high-temperature stabilization on the microstructure and tensile property of severely deformed Al-Mg-Sc alloy

In this paper, the effect of short-time high-temperature stabilization on the microstructure and tensile property of the Al-Mg-Sc alloy deformed by equal channel angular pressing (ECAP) has been investigated. The results show that the 2-pass ECAP cannot completely refine the grain, and the distribution of the deformed structure is inhomogeneous. After short-time stabilization, the grain of the material is refined, the shear zone becomes small grains with a size of about 1 μm, and the non-uniform deformation structure is alleviated. This change results in a small reduction in strength but a large increase in toughness. Short-time stabilization also improves the workability of the material. Re-deforming the material by another 2 pass ECAP, the sample with short-time stabilization demonstrates fewer internal defects, a more uniform structure, and finer grains.

The Quantitative Evaluation of the Cell Structure Uniformity of Microcellular TPU with Low Porosity via a Digital Image Processing Method.

The cell structure uniformity of microcellular polymers significantly impacts material performance, especially for low-porosity microcellular TPU used in chip polishing. The distribution of the cell structure of polishing pads directly affects the removal rate and process repeatability. Despite its importance, no quantitative method for evaluating cell structure uniformity has been reported in the literature. In this study, a digital image processing method that involves morphological operations of scanning electron microscopy (SEM) images, binarization, and cell localization, and the statistical evaluation of cell structure parameters was established to evaluate cell structure uniformity. A quantitative metric, the cell structure uniformity index (CUI), was calculated based on cell structure indices, incorporating the cell size index (Ud), the cell number index (Un), and the cell local spacing index (Ur). By establishing an ideal model and analyzing representative SEM images, the effectiveness and efficiency of the method for evaluating cell structure uniformity of microcellular TPU were successfully validated. The results demonstrated that low-porosity TPU foams exhibited relatively low cell structure uniformity compared to the ideal model. The heterogeneous nucleation process in TPU caused non-uniform cell structures due to the temporal and spatial non-homogeneities during the early cell nucleation process. As the cells grew, they merged and reduced the distance between them, resulting in improved cell structure uniformity.