Unoptimized Structure Research Articles

Equal heat flux loading optimization approach for uniform wear of the wet brake

Due to their exceptional ability to endure heavy loads, cam-lobe radial-piston hydraulic motors are extensively utilized in heavy machinery. The wet brake is a key part capable of providing highly braking torque, which has numerous friction pairs and a compact structure. However, there exists a challenge in solving the issue of irrational pressure distribution which leads to non-uniform heat flux distribution and severe wear failure of the brake discs. For this, an innovative method to optimize the wet brake's loading structure has been developed to address the issue of non-uniform heat flux distribution. A thermomechanical coupling finite element (FE) model was established to establish a clear correlation between loading structure parameters and contact pressure distribution on the brake disc. An innovative equal heat flux criterion was introduced to guide the optimization process. Simulation results confirmed that the optimized loading structure achieved a brake disc contact pressure distribution aligned with the ideal heat flux density criteria. Experimental validation further demonstrated a notable reduction of up to 44.39 % in maximum wear depth (hmax) across different radii of the brake disc compared to the unoptimized structure. These findings underscore the efficacy of our approach in reducing wear rates and enhancing durability of the wet brakes.

Understanding Performance Limitation of Liquid Alkaline Water Electrolyzers

Liquid alkaline water electrolyzers (LAWEs), being the most commercially mature electrolysis technology, play a pivotal role in large-scale hydrogen production. However, LAWEs suffer from low operational efficiency, primarily due to un-optimized electrode structure and chemical compositions. Thus, we investigated how various electrode configurations could impact LAWE performance. Our results show that Ni felt electrodes outperform the conventional Ni foam thanks to improved electrochemical active surface area (ECSA) and preferred electrode surface structure that minimizes the micro-gaps in between the electrode and separator. By comparing the stainless steel (SS) felt electrodes with Ni felt electrodes, SS not only shows better oxygen evolution reaction activity but also improved hydrogen evolution reaction activity, which is less studied in the literature. We also show that a bilayer structure with small pore radius facing the separator could further improve LAWE performance by further optimizing interfacial contact between electrode and separator. These findings enable LAWEs to sustain 2 A cm−2 at 2.2 V and operate steadily at 1 A cm−2 for nearly 600 h with negligible performance decay. Our studies establish criteria for selecting electrodes to achieve high-performance LAWE and, in turn, expedite the adoption of LAWEs in hydrogen production and the transition towards low-carbon economies.

Barrier and channel thickness engineering to optimize fin height for enhancement mode Al0.3Ga0.7N/GaN FinHEMT

AbstractIn this work, a thorough analysis of the Al0.3Ga0.7N/GaN FinHEMT structure has been performed using three‐dimensional numerical simulations to achieve enhancement mode (E‐mode) operation. In the proposed optimized structure, the fin height (HFin) is comprised of 7 nm critical strained AlGaN barrier layer with 30% Al mole fraction and 63 nm GaN channel layer having a fixed fin width (WFin) of 160 nm. The two‐dimensional electron gas (2DEG) concentration near the hetero interface is found to vary inversely with HFin of the proposed structure. The 2DEG variation was compared between fin‐shaped full tri‐gate approach and variable side gate length tri‐gate design counterpart for a fixed HFin of 70 nm. We achieved an improved threshold voltage of −0.2 V in the optimized HFin structure as compared to −1.45 V obtained in the unoptimized structure as reported earlier. Further, upon decreasing WFin to 40 nm in the same structure having optimized HFin of 70 nm, an E‐mode operation was achieved with a positive threshold voltage of 0.4 V. The positive shift in threshold voltage is explained with the help of necessary energy band diagram.

Optimization of an Air-cooling Thermal Management System for Lithium-ion Battery Packs via Particle Swarm Algorithm

Recently, lithium-ion batteries have attracted many researchers and their safety issues such as overheating, combustion and explosion continue to further limit battery application scenarios. These issues are mainly caused by unoptimized battery structure parameters or cooling methods. In this paper, an integrated approach has been proposed to design an efficient air-cooling system using the particle swarm algorithm to find an optimal relationship between air flow rate and battery temperature. Firstly, this method can adjust an optimized air flow rate to ensure that the battery temperature is minimized with the lowest energy consumption via the particle swarm algorithm. Additionally, an optimized air flow rate can still be obtained with the change of structure parameters such as the radius in a lithium-ion battery pack via this novel algorithm. Then, we demonstrate the feasibility of this integrated method in simulations. Compared with the previous work, this method can employ the continuous modulation of the particle swarm algorithm, realizing both the best cooling capacity of the battery cooling system and simultaneously the lowest energy consumption for cooling in cell heat regulation systems. Meanwhile, temperature variations of the entire cell pack are also shown in simulations. In contrast to previous approaches, this integrated method may provide more dynamic thermal management inspirations for designing novel battery thermal management systems.

Design and Analysis of an Axial Center-Piercing Hydrocyclone

To enhance the separation efficiency of downhole oil–water hydrocyclones in co-produced wells, an axial center-piercing hydrocyclone structure is proposed. A mathematical relationship model between the structural parameters and separation efficiency of the axial center-piercing hydrocyclone is constructed based on the response surface methodology. The numerical simulation method is employed to analyze both the unoptimized and optimized hydrocyclone structures, and their separation performances are simulated under identical operational conditions. The results indicate that the optimal structural parameter values are as follows: main diameter D = 70.4 mm, large cone angle α1 = 32.4°, small cone angle α2 = 3.9°, bottom flow tube length L3 = 311.7 mm, and inverted cone length L4 = 166.0 mm. The optimal operation parameters of the optimized structure are also obtained. Under the same operating parameter conditions, the separation efficiency of the optimized structure is consistently higher than that of the unoptimized structure. The highest efficiency achieved by the optimized structure is 98.6%, which is a 2% improvement over the unoptimized state. Finally, experiments are conducted with the optimized hydrocyclone separator structure under different split ratios. This study significantly contributes to the field of injection and production in a single well, particularly in promoting the application of hydrocyclones.

Design and Fabrication of PVDF Based Flexible Piezoelectric Vibration Energy Harvester

In this work, a novel petal-shaped substrate with a trapezoidal active layer Flexible Energy Harvester(FEH) is modeled using an analytical equation. The trapezoidal shape piezoelectric layer’s geometric parameters are optimized using the Nelder-Mead(NM) method. The active layer PVDF films are fabricated using the solution casting method. The NM-optimized geometry generates a voltage of 1.9 V compared with the un-optimized structure. The three different proof mass shapes cube, ellipsoid, and cylindrical are utilized to tune the resonant frequency. The NM-optimized geometry with cylindrical proof mass provides open circuit AC voltage of 3.68 V at very low frequency air-conditioner vibration.

Morphological Control of Supported ZnO Nanosheet Arrays and Their Application in Photodegradation of Organic Pollutants.

Supported nanostructured photocatalysis is considered to be a sustainable and promising method for water pollution photodegradation applications due to its fascinating features, including a high surface area, stability against aggregation, and easy handling and recovery. However, the preparation and morphological control of the supported nanostructured photocatalyst remains a challenge. Herein, a one-step hydrothermal method is proposed to fabricate the supported vertically aligned ZnO nanosheet arrays based on aluminum foil. The morphologically controlled growth of the supported ZnO nanosheet arrays on a large scale was achieved, and the effects of hydrothermal temperature on morphologic, structural, optical, and photocatalytic properties were observed. The results reveal that the surface area and thickness of the nanosheet increase simultaneously with the increase in the hydrothermal temperature. The increase in the surface area enhances the photocatalytic activity by providing more active sites, while the increase in the thickness reduces the charge transfer and thus decreases the photocatalytic activity. The influence competition between the area increasing and thickness increasing of the ZnO nanosheet results in the nonlinear dependence between photocatalytic activity and hydrothermal temperature. By optimizing the hydrothermal growth temperature, as fabricated and supported ZnO nanosheet arrays grown at 110 °C have struck a balance between the increase in surface area and thickness, it exhibits efficient photodegradation, facile fabrication, high recyclability, and improved durability. The RhB photodegradation efficiency of optimized and grown ZnO nanosheet arrays increased by more than four times that of the unoptimized structure. With 10 cm2 of as-fabricated ZnO nanosheet arrays, the degradation ratio of 10 mg/L MO, MB, OFL, and NOR was 85%, 51%, 58%, and 71% under UV irradiation (365 nm, 20 mW/cm2) for 60 min. All the target pollutant solutions were almost completely degraded under UV irradiation for 180 min. This work offers a facile way for the fabrication and morphological control of the supported nanostructured photocatalyst with excellent photodegradation properties and has significant implications in the practical application of the supported nanostructured photocatalyst for water pollution photodegradation.

Aeroelastic tailoring of composite rudder skin considering variable angle tow laminates by a hybrid backtracking search-JAYA-Sine Cosine Algorithm

Flutter is a typical dynamic instability phenomenon of the wing or rudder structure. Besides, the phenomenon of aerodynamic heating will be quite significant and temperature can rise rapidly with the increase of the flight speed, thermal flutter characteristics should be taken into consideration for the rudder structure of supersonic vehicle. To improve the thermal flutter characteristics of the rudder structure and meet the design requirements of a lightweight structure, this article optimizes the variable stiffness laminates of the skin on the premise of keeping the thickness of the skin unchanged, so as to improve the critical flutter speed of the rudder. A novel intelligent optimization algorithm named BJASCA, which is a hybrid algorithm coupling of Backtracking Search Algorithm, Sine Cosine Algorithm, and JAYA Algorithms is proposed in this article to improve the efficiency of structural optimization and this algorithm shows obvious advantages in searching global optima compared with several other algorithms. The finite element model and aerodynamic model of the rudder are established to calculate the critical flutter speed. The results represent that the rudder structure optimized by the BJASCA algorithm shows better flutter characteristics and the critical flutter speed can be increased by 76.4% compared with the un-optimized structure.

Optimization of landscape spatial structure aiming at achieving carbon neutrality in desert and mining areas

Carbon neutrality is a long-term climate goal in the context of global warming and can be achieved by reducing carbon emissions and increasing carbon sinks. Vegetation has a very important and irreplaceable role in increasing carbon sinks, but it is often destroyed, especially in desertification and mining areas. Therefore, restoration of the vegetation in these areas is essential. Seeking the optimal solution for landscape spatial structure through adjustment and optimization can promote ecological processes, improve environment and soil conditions on a large scale, provide favorable conditions for vegetation growth, and is an effective way to achieve vegetation restoration to increase carbon sinks. Here, a targeted landscape spatial structure optimization scheme called EFCT model was developed for complex ecological situation of Ordos, with the goal of increasing carbon sinks to achieve carbon neutrality. The scheme identified areas where the landscape spatial structure needs to be optimized and the direction of optimization based on the differences in the synergy degree between ecological function and connectivity of the patches. The study also compared the carbon sink function and robustness of the landscape spatial structure before and after optimization according to the scheme. The results show that the patches in the landscape spatial structure of Ordos form four separate clusters distributed in a differentiated east-west part of the structure, with higher ecological function and poorer connectivity in the east and the opposite in the west. In the landscape spatial structure optimized by the EFCT model, the ecological function of 42 patches was enhanced, and 19 patches and 44 corridors were added. The total carbon sink in the optimized structure increased by 31.51% compared to the unoptimized structure, mainly due to the improved ecological function of the grassland patches in the western structure, in addition to the carbon sink contribution of the new patches and corridors. At the same time, the connectivity between the four clusters had been enhanced and the structure was more coherent and stable.

7.1: Invited Paper: Establishment and Simulation Optimization of Optical Fingerprint Recognition Structure in LCD Screen

This paper reports a new type of liquid crystal screen which has an in‐screen optical fingerprint recognition collimation structure. The collimator structure in the TFT&CF glass in the screen has different opening size and height. Through simulation, the SNR(Signal to Noise Ratio)&CR(contrast ratio) evaluation criteria were obtained to judge the fingerprint identification accuracy of the collimating structure. Compared with the unoptimized structure, the optimized collimation layer improves the accuracy of fingerprint identification.

Optimized InAlAs graded buffer and tensile-strained dislocation filter layer for high quality InAs photodetector grown on Si

We demonstrate a low threading dislocation density (TDD) and smooth surface InAs layer epitaxially grown on Si by suppressing phase separation of InxAl1−xAs (x = 0 to 1) graded buffer and by inserting a tensile-strained In0.95Al0.05As dislocation filter layer. While keeping the total III–V layer below 2.7 μm to avoid thermal cracks, we have achieved a sixfold reduction of TDD in InAs on Si compared to the unoptimized structure. We found a strong correlation between the metamorphic InAs surface roughness and TDD as a function of InxAl1−xAs buffer thickness. An optimal thickness of 175 nm was obtained where both phase separation and 3D islanding growth were suppressed. Moreover, a tensile-strained In0.95Al0.05As dislocation filter layer and high growth temperature of the InAs cap layer further assisted the dislocation reduction process, which led to a TDD to 1.37 × 108 cm−2. Finally, an InAs p-i-n photodetector grown on the optimized InAs/Si template confirmed its high quality by showing an improved responsivity from 0.16 to 0.32 A/W at a 2 μm wavelength.

TOPOLOGICAL DESIGNING AND ANALYSIS OF THE COMPOSITE WING RIB

The composite structures in the aerospace industry for in recent decades are widely applied however, at the beginning of the 21st century composites are growing rapidly. The largest companies in the aerospace industry are increasing the volume of composites application of in the structures, and nowadays the volume of composites reaches 50%. The different elements of aircraft and even highly loaded structures such as spars, ribs, skin, etc., are currently made from composites. First of all, this is due to the possibility of a significant reduction in the weight of the structure, as well as a decreasing in production costs. The advanced technologies in the engineering software allows to solute different complex problems. One of the main direct of research in the composites is optimization of composite structure due to improving the relative strength and relative stiffness of the composite structure, and improving the efficiency of manufacturing processes. There are a lot of methods of optimizations but currently the topological optimization is the most conceptual and forward-looking method. The main goal of the article is to analyze and estimate the approach for designing wing rib with symmetric laminated plates with the different fiber orientation based on the topology optimization. The following tasks were solved for this: firstly, a topological optimization model was determined. This model was based on maximum stiffness with a specified volume constraint is established. The next step was optimization by the solid isotropic material with penalization (SIMP) model and sensitivity filtering technique; as a result of optimization the topological structures of wing rib with different fibre orientations were obtained. The topological structure and stiffness of the wing rib depend on the fibre orientation. Finally, the corresponding morphing analysis of wing rib with laminated plates is implemented by adopting ANSYS, which verified the anti-deforming capability of topology structure and illustrated the feasibility for designing the wing rib. The result shows that the maximum deformation of optimized structure is 1.57mm, whereas the maximum deformation of the un-optimized structure is 2.02 mm. Under the condition of the same material removals, the optimized structure can decrease by more than 20% deformations.

42‐2: Establishment and Simulation Optimization of Optical Fingerprint Recognition Structure in LCD Screen

This paper reports a new type of liquid crystal screen which has an in‐screen optical fingerprint recognition collimation structure. The collimator structure in the TFT&CF glass in the screen has different opening size and height. Through simulation, the SNR( Signal to Noise Ratio )&CR(contrast ratio) evaluation criteria were obtained to judge the fingerprint identification accuracy of the collimating structure .Compared with the unoptimized structure, the optimized collimation layer improves the accuracy of fingerprint identification.

Development of an ion beam measurement instrument for divertor simulation experiments in radio-frequency plasma

A retarding field analyzer (RFA) that consists of three grids and a collector was developed, and the measurement of an ion beam that passes through plasma was demonstrated. First, a suitable grid potential structure to allow the measurement of an ion beam in plasma was investigated. After this investigation, a helium ion beam was measured without the production of plasma. It was found that the helium ion beam current was significantly overestimated when an unoptimized potential structure was utilized. One probable reason for the overestimation is secondary electron emission. Next, ion beam measurement in low density helium ionizing plasma was conducted. Accompanying the onset of the beam extraction, the collector current clearly increased, which implies that the beam ions penetrated through the plasma and reached the RFA. Subsequently, similar measurements were conducted after the electron density of the helium plasma was changed. Since a nearly identical beam extraction condition was retained, the ion beam current obtained after plasma production was almost constant. However, the ion beam current obtained during plasma production increased as the electron density increased. A calculation of the ion beam envelope indicated that space charge neutralization by bulk electrons could account for the increase in the ion beam current.

STRUCTURE OPTIMIZATION OF DEEP BELIEF NETS IN THE APPLICATIONS OF IMAGE RECOGNITION.

Deep belief network (DBN) has become one of the most important models in deep learning, however, the un-optimized structure leads to wasting too much training resources. To solve this problem and to investigate the connection of depth and accuracy of DBN, an optimization training method that consists of two steps is proposed. Firstly, by using mathematical and biological tools, the significance of supervised training is analyzed, and a theorem, that is on reconstruction error and network energy, is proved. Secondly, based on conclusions of step one, this paper proposes to optimize the structure of DBN (especially hidden layer numbers). Thirdly, this method is applied in two image recognition experiments, and results show increased computing efficiency and accuracies in both tasks.

Metal-Assisted Delayed Fluorescent Pd(II) Complexes and Phosphorescent Pt(II) Complex Based on [1,2,4]Triazolo[4,3-a]pyridine-Containing Ligands: Synthesis, Characterization, Electrochemistry, Photophysical Studies, and Application.

The synthesis and photophysical characterization of a series of tetradentate cyclometalated M(tzpPh-O-CzPy-R) complexes and their analogues are reported, where M is palladium or platinum and a tetradentate cyclometalating ligand contains tzpPh (3-phenyl-[1,2,4]triazolo[4,3-a]pyridine) and CzPy (carbazolylpyridine) moieties linked with an oxygen atom. Variations of the σ-electron-donating group R on the ligand significantly affect the photophysical properties of the complexes. By using the strong electron-withdrawing tzp portion as an acceptor and the carbazole portion as a donor, a series of Pd(II)-based metal-assisted delayed fluorescence (MADF) materials was developed. Electrochemical analysis demonstrates the irreversible reduction process occurs on the tzp ring and the irreversible oxidation process mainly occurs on the metal-phenyl moiety. This is in agreement with the HOMO and LUMO distributions by the DFT calculations, which also shows that the Pt(II) complex has more metal orbital character than those of the Pd(II) complexes. Most of the Pd(II) complexes reported here are highly emissive at 77 K in 2-MeTHF with luminescent lifetimes in the millisecond range (τ = 1.96-2.36 ms) and λmax = 488-499 nm; however, the luminescent lifetimes are shortened to the microsecond range (τ = 26.7-152.9 μs in solution and 57.0-109.9 μs in thin film respectively) at room temperature. The quantum efficiency of the Pd(II) complexes can be increased by more than 8-fold through structure modification with σ-donating groups on the ligand. Especially, the Pd(tzp-3) has a small ΔEST of 0.228 eV and exhibits strong typical MADF in PMMA film. The Pt(II) complex Pt(tzp-2) exhibits high thermal stability (ΔT0.5% = 440 °C) and high quantum efficiency (Φ = 50.1%) in dichloromethane solution with τ of 15.8 μs. The Pt(tzp-2) based bright green OLED achieved a peak EQE of 8.7% and a maximum brightness of 28280 cd/m2 using an unoptimized device structure.

Insights into photocatalytic CO2 reduction on C3N4: Strategy of simultaneous B, K co-doping and enhancement by N vacancies

C3N4 is a promising non-metal photocatalyst for CO2 conversion to value-added products, while it shows unsatisfactory performance due to the low CO2 adsorption ability and poor utilization of the photo-excited charge carriers. The deficiency of electron donation sites and unoptimized electronic structure are the primary reasons behind. To address the challenges, herein, we propose a new synthesis strategy of rational co-doping of B, K elements in line with controllable introduction of Nv into C3N4 within one step during synthesis. The synergistic effects of the modification factors resulted in an enhanced C3N4 catalyst with an electron-rich surface and tailored electronic structure, which significantly facilitated the CO2 adsorption and activation in sequence. Moreover, the drawback of single element doping is largely avoided due to the synergistic effects provided by this rational multiple modification strategy. A 5-h photocatalytic production of 5.93 μmol g−1 CH4 and 3.16 μmol g−1 CO respectively were achieved using CO2 and H2O as feedstocks without the presence of any organic hole scavenger, which are 161% and 527% of CH4 and CO produced by pristine C3N4.

Achieving High 1H Nuclear Hyperpolarization Levels with Long Lifetimes in a Range of Tuberculosis Drug Scaffolds

Despite the successful use of isoniazid, rifampicin, pyrazinamide and ethambutol in the treatment of tuberculosis (TB), it is a disease of growing global concern. We illustrate here a series of methods that will dramatically improve the magnetic resonance imaging (MRI) detectability of nineteen TB-relevant agents. We note that the future probing of their uptake and distribution in vivo would be expected to significantly enhance their efficacy in disease treatment. This improvement in detectability is achieved by use of the parahydrogen based SABRE protocol in conjunction with the 2 H-labelling of key sites within their molecular structures and the 2 H-labelling of the magnetization transfer catalyst. The T1 relaxation times and polarization levels of these agents are quantified under test conditions to produce a protocol to identify structurally optimized motifs for future detection. For example, deuteration of the 6-position of a pyrazinamide analogue leads to a structural form that exhibits T1 values of 144.5 s for 5-H with up to 20 % polarization. This represents a >7-fold extension in relaxation time and almost 10-fold improvement in polarization level when compared to its unoptimized structure.

Optimization of compound serpentine–spiral structure for ultra-stretchable electronics

Stretchable electronics is a rising technology, promising to replace the conventional, brittle and rigid electronics for applications that demand mechanical compliance to irregular, complex and mobile shapes. Several approaches have been proposed to find an optimum balance between electrical and mechanical characteristics. These include finding new flexible electronic materials, integrating both organic and inorganic materials or incorporating structural modifications to conventional materials, thus achieving flexibility and stretchability. Previously, the use of spiral-based structures made entirely out of silicon, a well-mature and high-performing material, has been proposed as a platform for ultra-stretchable electronic applications. In this paper we have demonstrated the use of spiral-based compound, fractal-inspired structures to optimize and greatly reduce the stress and strain distribution along them. The integration of double-arm spirals with variants of serpentine and horseshoe structures has been considered and their mechanical response to an applied deformation has been performed through finite element analysis (FEA). The proposed compound structures provide outstanding stretching capabilities and demonstrate up to ∼55% reduction in stress/strain, as well as a more uniform distribution as compared to the original, un-optimized spiral-based structure. These results show the remarkable potential of combining structures to optimize their mechanical behavior, thus accomplishing more robust platforms that will leverage the development of stretchable electronics.

Radial p-n junction macroporous silicon solar cell on p-type upgraded metallurgical-grade silicon substrate

Macroporous silicon was fabricated on p-type upgraded metallurgical-grade (UMG) c-Si substrate with the resistivity of about 0.1–3 Ω cm, by metal-catalyzed electrochemical etching (MCECE). Ag nanoparticle catalyst was first fabricated on the c-Si substrate. Then, the electrochemical etching was performed. By optimizing the MCECE processes carefully, the macroporous silicon was successfully obtained with the pore width up to about 400 nm and the pore depth of 2–5 μm. After that, the radial amorphous/crystalline silicon heterojunction (SHJ) structure was prepared by conformally depositing a-Si:H i-layer and n-layer on the macroporous silicon via plasma-enhanced chemical vapor deposition (PECVD) at 200 °C, followed by depositing indium tin oxide front contact and Ag back contact via magnetron sputtering and thermal evaporation, respectively. As a result, the demonstrated radial p-n junction macroporous silicon solar cell with the unoptimized SHJ structure gave out a conversion efficiency of 3.67% under the standard AM1.5 illumination, which indicated a potential to make high performance radial p-n junction solar cell on UMG c-Si substrate.