Optimal Structure Research Articles

Numerical study on the combined application of multiple phase change materials and gradient metal foam in thermal energy storage device

Latent heat thermal energy storage (LHTES) offers significant energy-saving benefits, but its application is limited due to the low thermal conductivity of phase change material (PCM). To address this issue, this article studied the combined application of metal foam structures with different porosity gradients and multiple PCMs with different melting points through numerical simulation to accelerate the melting of PCM and enhance system efficiency. The results showed that the application of multiple PCMs improved the heat transfer performance of the system, reducing the complete melting time by 9.18% compared to using a single PCM with uniform metal foam. Based on the multi-PCM storage system with an average porosity of 0.90, this article designed metal foam structures with one-dimensional and two-dimensional porosity gradients and explored their impacts. The results indicated that in the structure with a one-dimensional porosity gradient along the heat flow direction, the positive gradient decreased thermal resistance, further reducing the complete melting time by 6.18%, while the negative gradient increased it by 19.78%. However, the temperature non-uniformity was lowest with the negative gradient and highest with the positive gradient. The optimal two-dimensional porosity gradient multi-PCM storage model not only reduced thermal resistance but also effectively solved the issue of uneven melting, reducing the complete melting time by 17.96% and increasing the energy storage efficiency by 20.16% compared to the single PCM system with uniform porosity. Furthermore, the article conducted a dimensionless analysis of the optimal structure and different gradient structures, establishing formulas for the liquid fraction concerning modified Fourier number, modified Stefan number, and modified Rayleigh number.

Strategic integration of metamaterials properties and topology optimization of gyroid metal hydride reactor for high-density hydrogen storage

Metal hydride (MH) is considered to be one of the potential materials for storing hydrogen. It has a substantial limitation to wide use in the mobility sector, which is its low gravimetric hydrogen storage density. A novel canister design utilizing the optimization of gyroid structure for MH-based hydrogen storage is proposed to enhance reactor strength and capacity, increasing the favor of using it outside stationary applications. Topology optimization (TO) of the reactor increases the capacity by 49 % while maintaining the capability of this reactor to sustain 5000 N of bending case. On top of that, changing the metamaterial properties of the gyroid results in a larger chamber size for storing a larger amount of MH by the maximum amount of 30 %. However, increasing the chamber size comes with a cost of a lower charging rate and a considerable area of non-reacted hydride at the same charging time compared to the non-modified structure. By evaluating the MH bed that consists of lanthanum nickel (LaNi5), the topologically optimized reactor design is varied with different chamber offsets of 0, 2, and 4 mm. The results show that using a 2 mm offset in this study case can increase hydrogen storage capacity by 22 % while maintaining the same charging time of less than 4500 s. The combination of both proposed methods can increase the overall MH bed chamber by 66.22 % compared to previous initial research that acts as proof of concept.

Optimization of Channel Structure of Alkaline Water Electrolyzer by Using Expanded Mesh as Bipolar Plate

Optimization of Channel Structure of Alkaline Water Electrolyzer by Using Expanded Mesh as Bipolar Plate

The Influence of Rural Ecological Environment Development by China's Industrialization Process

This article aims to solve the problem of heavy pollution load in rural ecological environment at present. This article elaborates on the relevant concepts and theories of rural industrialization and ecological environment protection, mainly using a combination of qualitative and quantitative methods to analyze the current situation of rural ecological environment pollution in the research area. The research results indicate that the current rural ecological environment pollution load in China is heavy and severe, especially the use of fertilizers, pesticides, agricultural plastic films, livestock and poultry breeding, rural life, and township enterprise production, which have caused varying degrees of harm to the regional rural ecological environment. Therefore, effective measures must be taken to achieve the organic combination of rural industrialization and ecological environment protection. This article provides guidance for promoting the optimization and upgrading of rural industrial structure, achieving a win-win situation of economic and ecological benefits.

Self-draining microchannel surface structure for droplet condensation with controlled droplet radius distribution

Surface dewetting is technically important in industrial applications, particularly where phase change processes are involved. We present an intrinsically driven water-permeable microchannel surface system. It has two important advantages: its self-draining capability to remove surface droplets and its ability to limit both the maximum size of droplets condensing on the surface and the thickness of the water film in the microchannel system. This results in a reduction in the overall thermal resistance of the condensate on the cooled surface. We have successfully applied this surface drainage concept to water condensation. An improved condensation efficiency of 5%–9% has been achieved operating the device in an environmental chamber (60% relative humidity, 30 °C chamber temperature, 6 °C cooling temperature) without any optimization of the stable surface structure involved.

Optimum Design of InGaN Blue Laser Diodes with Indium-Tin-Oxide and Dielectric Cladding Layers.

The efficiency of current GaN-based blue laser diodes (LDs) is limited by the high resistance of a thick p-AlGaN cladding layer. To reduce the operation voltage of InGaN blue LDs, we investigated optimum LD structures with an indium tin oxide (ITO) partial cladding layer using numerical simulations of LD device characteristics such as laser power, forward voltage, and wall-plug efficiency (WPE). The wall-plug efficiency of the optimized structure with the ITO layer was found to increase by more than 20% relative to the WPE of conventional LD structures. In the optimum design, the thickness of the p-AlGaN layer decreased from 700 to 150 nm, resulting in a significantly reduced operation voltage and, hence, increased WPE. In addition, we have proposed a new type of GaN-based blue LD structure with a dielectric partial cladding layer to further reduce the optical absorption of a lasing mode. The p-cladding layer of the proposed structure consisted of SiO2, ITO, and p-AlGaN layers. In the optimized structure, the total thickness of the ITO and p-AlGaN layers was less than 100 nm, leading to significantly improved slope efficiency and operation voltage. The WPE of the optimized structure was increased relatively by 25% compared to the WPE of conventional GaN-based LD structures with a p-AlGaN cladding layer. The investigated LD structures employing the ITO and SiO2 cladding layers are expected to significantly enhance the WPE of high-power GaN-based blue LDs.

Effects of space-confined ratio on the MILD combustion of coke oven gas

The objective of this study is to investigate the effects of the spatial structure on MILD combustion characteristics of coke oven gas via numerical simulation. The space-confined ratio, defined as the ratio of the furnace height to the longest diagonal of the transverse section, is used to characterize the variation in spatial structure. An experimental study in a long-narrow confined furnace (LNCF) was initially conducted to investigate the conditions for achieving MILD combustion. Subsequently, the effects of spatial structure on MILD combustion characteristics were thoroughly investigated through numerical simulation by altering the space-confined ratio of the LNCF. The experimental results show that the transition from conventional combustion to MILD combustion is achieved at a dilution rate of 50 %, which improves the temperature uniformity and reduces the NO emission by 96.5 % to 3 ppm. The numerical results show that reducing the space-confined ratio enhances the flue gas internal recirculation and the temperature uniformity, especially the maximum temperature is significantly reduced. Moreover, reducing the space-confined ratio achieves nearly zero NO emissions, but an excessively space-confined ratio may result in incomplete combustion, consequently causing a significant rise in CO emissions. To guarantee complete combustion, the optimal furnace structure is achieved at a space-confined ratio of 6.4, ensuring not only temperature uniformity but also ultra-low emissions of NO and CO. Therefore, this study provides a theoretical and practical foundation for the ultra-low emission of pollutants in space-confined combustion systems.

Performance optimization of a neon turboexpander based on the Kriging model and genetic algorithm

The rapid development of high-temperature superconducting (HTS) technology has increased demand for stable and reliable cooling sources, with the neon refrigerator emerging as a favorable solution for HTS applications, among which neon turboexpander is the core component. This paper proposes an optimal design method tailored for the neon turboexpander, which combines a one-dimensional mean-line design, three-dimensional CFD analysis, adaptive Kriging surrogate model, and the genetic algorithm. The meridional contour of the turboexpander impeller is geometrically parameterized, and the three most critical structural parameters are selected through Sobol sensitivity analysis, and then the response surface analysis is carried out to analyze the coupling relationship between the structural parameters. After optimization, the total-to-static efficiency and output power of the neon turboexpander increased by 3.98% and 6.12%, respectively. Notably, the flow separation phenomenon within the optimized impeller is significantly improved, resulting in reduced flow loss. Furthermore, the optimized impeller demonstrates robust performance in a wide range of variable operating conditions. Therefore, the optimization design method has been proven effective, and the optimal turboexpander impeller structure can be obtained quickly and accurately.

Prediction method for re-damage behavior of the repaired CFRP bolted joint

Composite materials are widely used in various aircraft due to their high specific strength, stiffness, corrosion resistance, and robust design flexibility. However, when subjected to complex loading conditions, composite structures are susceptible to damage, necessitating prompt repair upon aircraft return. Analyzing the re-damage process of repaired structures is crucial for assessing aircraft structural reliability, lifespan, and determining whether a repeat flight is warranted. In this study, a prediction method was proposed for re-damage behavior through meso-modeling and energy analysis of the repaired composite bolted joint. First, this article established a meso-mechanical model for composite laminates, analyzed force transfer characteristics at the fiber − matrix interface, and derived equations for stress field. Additionally, a strain energy distribution model was developed for composite bolted repaired joint near fibers and repaired area, proposing a damage prediction method based on the strain energy criterion. This method could anticipate the location, type, sequence, and magnitude of damage. Finally, simulation calculations yielded mechanical characteristics of the repaired area under typical load conditions, while loading tests verified the feasibility of the prediction method. This study offered an effective means of predicting performance degradation in composite structures and provided a vital direction for optimal spacecraft structure repairing methods and parameters.

A Review on Application of Pin-Fins in Enhancing Heat Transfer

The pin-fin is one of the main technologies in enhancing heat transfer. The accelerated flow and vortex structures are produced, which can disrupt the development of the flow boundary layer. The configuration of the pin-fin is obvious for heat transfer and flow characteristics, including its shape, size, and arrangement in the cooling channel. This work provides a detailed introduction to the application of pin-fins in enhancing heat transfer and reducing flow resistance, including the conventional shapes, improved shapes based on circular pin-fins and irregular shapes. At the same time, the influence of the diameter, height and density of pin-fins on heat transfer and flow performance is studied, and the influence mechanism is analyzed from the perspective of boundary layers. In addition, some applications that combine pin-fins with other cooling methods to further improve performance are analyzed. In terms of the optimization technology, the structure optimization for pin-fin shape and the layout optimization for pin-fin array are summarized. Therefore, this review provides a wide range of literature for the design of internal cooling channel pin-fins.

Effect on the physical field of the die during the backward extrusion process of magnesium alloy wheel

The eccentric placement of billets reduces the service life of the dies, and at the same time causes the scrapping of the wheel blanks. However, for axisymmetric forgings, eccentric placement is unavoidable. In this study, the mutual effects between the billet and the die during backward extrusion of magnesium (Mg) alloy wheels are analyzed by physical and numerical simulations, focusing on the effects on the physical field of the die. There were dangerous points in the design of the combined die structure and the lower mating surface of the female die and the bottom die were prone to stress concentration during the filling process of the Mg wheel, which led to the cracking of the die. The eccentric extrusion of the wheel resulted in a slope in the filling height of the rim, and it had a great effect on the physical field and microstructure distribution at the same time, which in turn affected the physical field distribution of the wheel die, resulting in uneven load distribution at the lower rim of the die and reducing the life of the combined die. The combined die structure optimization solution can process the female die into a curved surface along the fracture surface and at the same time process a hollow circular table to cooperate with the bottom die and the female die.

Mesoporous Hollow Carbon Sphere-Embedded MXene Architectures Decorated with Ultrafine Rh Nanocrystals toward Methanol Electrooxidation.

The development of advanced Pt-alternative anode electrocatalysts with high activity and reliable stability is critical to overcoming the technical challenges of direct methanol fuel cells. Here, we propose a robust bottom-up strategy for the spatial construction of mesoporous hollow carbon sphere (HCS)-embedded MXene architectures decorated with ultrafine Rh nanocrystals (Rh/HCS-MX) via stereoscopic coassembly reactions. The rational intercalation of HCS effectively separates the MXene nanowalls to achieve a rapid mass-transfer efficiency, while the intimate coupling of the hybrid carrier with Rh nanocrystals enables their electronic structure optimization, thus contributing to strong synergistic catalytic effects. Accordingly, the resulting Rh/HCS-MX architectures exhibit outstanding methanol electrooxidation properties in terms of large electrochemical active surface areas, high mass/specific activities, and good long-term stability, all of which are significantly superior to the traditional Rh/carbon black, Rh/HCS, and Rh/MXene as well as commercial Pt/carbon balck and Pd/carbon balck electrocatalysts.

Research of Bubble Breakup and Influencing Factors in Flotation Machine

As the core factor of flotation, bubbles have an important effect on flotation. The rotor speed, initial gas parameters and impeller structure of the flotation machine will affect the formation and movement of bubbles. It is very important to study the influence mechanism of operating parameters of flotation machine on the bubble breakup process for flotation machine design and structure optimization. This paper takes KYF-0.2m<sup>3</sup> flotation machine as the research object, establishes a single bubble analysis model, adopts the VOF (Volume of Fluid) method to analyze the influence of different initial positions of bubbles on the bubble breakup behavior, and studies the influence of impeller speed and initial position of bubbles on the bubble breakup. Result show that the breakup of bubbles mainly occurs near the stator region. With the increase of rotational speed of the impeller, the centrifugal force and the disturbance of the convection field will become greater, the time of the bubble breakup become shorter, more bubbles breakup and generate more smaller ones. With the bubble position is closer to the rotating axis of the impeller, the impact of reflow becomes stronger and the bubble breakup effect will be better, and if the bubble initial position closer to the impeller cover, the influence of impeller on the bubbles become greater and the distribution of bubbles will be more uniform.

Antibody-SGM, a Score-Based Generative Model for Antibody Heavy-Chain Design.

Traditional computational methods for antibody design involved random mutagenesis followed by energy function assessment for candidate selection. Recently, diffusion models have garnered considerable attention as cutting-edge generative models, lauded for their remarkable performance. However, these methods often focus solely on the backbone or sequence, resulting in the incomplete depiction of the overall structure and necessitating additional techniques to predict the missing component. This study presents Antibody-SGM, an innovative joint structure-sequence diffusion model that addresses the limitations of existing protein backbone generation models. Unlike previous models, Antibody-SGM successfully integrates sequence-specific attributes and functional properties into the generation process. Our methodology generates full-atom native-like antibody heavy chains by refining the generation to create valid pairs of sequences and structures, starting with random sequences and structural properties. The versatility of our method is demonstrated through various applications, including the design of full-atom antibodies, antigen-specific CDR design, antibody heavy chains optimization, validation with Alphafold3, and the identification of crucial antibody sequences and structural features. Antibody-SGM also optimizes protein function through active inpainting learning, allowing simultaneous sequence and structure optimization. These improvements demonstrate the promise of our strategy for protein engineering and significantly increase the power of protein design models.

The Information Cocoons in Military Decision Making and Strategies for Coping

As we all know, the information cocoon has a broad impact on people's basic cognitive abilities such as memory, decision-making, and judgment. This article first extends the concept of information cocoons to the field of command and decision-making behavior, and studies the harm and response measures of information cocoons to command and decision-making. The paper first elaborates on the causes of information cocoons, including technical factors, organizational structure factors, and psychological factors. Secondly, the harm of information cocoons to command decision-making was analyzed, including hindering accurate judgment of the battlefield situation, increasing battlefield risks, and increasing the likelihood of battlefield losses.Then, corresponding measures were proposed, including the application of technical means and optimization of organizational structure and decision-making processes. Finally, the importance of improving psychological resilience and leadership abilities was emphasized. The research conclusion of this article is helpful for command decision-makers to effectively overcome the challenges brought by the information cocoon to command decision-making and improve the correctness of decision-making.

A review of the development of YOLO object detection algorithm

The You Only Look Once (YOLO) algorithm series, as the forefront of object detection technology, has evolved from YOLOv1 to YOLOv10, consistently enhancing detection speed and accuracy. Through literature review and data analysis. This paper mainly discusses the development processes of the YOLO algorithm series, focuses on the changes and innovations in network structure, training strategies, and performance optimization. By introducing techniques, such as CSPNet, Anchor-free, data augmentation, and multi-scale training, the YOLO algorithm has progressively found a better balance between detection speed and accuracy, demonstrating excellent performance in processing real-time images and handling high-complexity scenarios. Furthermore, this paper also addresses some challenges faced by the YOLO algorithms and potential future research directions, such as the lower accuracy in detecting small targets and reduced robustness in complex scenarios. Through analysis, potential optimization directions for the future include further refining network structure and employing more efficient training methods to enhance algorithm efficiency. This paper intends to offer a thorough performance evaluation of the YOLO series algorithms, identify potential areas for future improvements to advance YOLO technology.

Enhanced Energy Storage Properties of Highly Polarized BMT-Based Thin Films through the Multiscale Structure Synergistic Regulation Strategy.

For solving the trade-off relationship of the polarization and breakdown electric field, ferroelectric films with high polarization are playing a critical role in energy storage capacitor applications, especially at moderate/low electric fields. In this work, we propose a multiscale structure (including defect, domain, and grain structures) synergetic optimization strategy to optimize the polarization behavior and energy storage performances of BiMg0.5Ti0.5O3 (BMT) ferroelectric films by introducing Sr0.7La0.2TiO3 (SLT) without compromising the breakdown strength. At a moderate electric field of 2917 kV/cm, a high discharge density of 72.2 J/cm3 has been achieved in 0.9BMT-0.1SLT films, together with good frequency, thermal, and cycle stabilities for energy storage. Importantly, the phase difference Δφ is utilized to quantitatively evaluate the polarization switching mobility of the ferroelectric domain/PNRs at an external electric field stimulation. This research demonstrates that a multiscale structure optimization strategy could effectively regulate the energy storage performance, and ecofriendly BMT-based materials are promising candidates for next-generation energy storage capacitors, especially at moderate/low electric fields.

Towards collaborative care for severe and enduring Anorexia Nervosa – a mixed-method approach

BackgroundSevere and Enduring Eating Disorders (SEED), in particular SEED-Anorexia Nervosa (SE-AN), may represent the most difficult disorder to treat in psychiatry. Furthermore, the lack of empirical research in this patient group, and, consequently the lack of guidelines, call for an urgent increase in research and discussion within this field. Meanwhile experts concur that effective care should be structured in a collaborative manner.ObjectiveTo identify the challenges in providing care to patients with SE-AN in the Dutch healthcare context, and propose a collaborative care treatment model to address these issues.MethodsA pragmatic mixed-method approach was used, structured as follows: (1) Identifying perceived barriers and treatment needs from the viewpoint of both patients and eating disorder healthcare professionals through an evaluation questionnaire; (2) Investigating current treatment practices for SEED/SE-AN via benchmarking; (3) Gaining insight into the optimal structure and content of care by interviewing network partners and experts-by-experience. Based on these findings, and drawing from literature on severe and enduring disorders, a treatment model for SE-AN was proposed and implemented.ResultsThe key challenges identified included a lack of knowledge about eating disorders among network partners, treatment ambivalence among patients and poor collaboration between professionals. The proposed model enhances self-management and collaborative relationships with healthcare providers, offers user-friendly and practical guidance, and aims at stabilization, reducing relapses, deterioration, and readmissions, thereby being cost-effective. Importantly, the model operates across levels of care (primary, secondary, tertiary).ConclusionThis study, describing a collaborative care program for SE-AN, developed and implemented in a highly specialized treatment center for eating disorders, sets the stage for further explanatory/efficacy research to build on the findings in this study, with the following aims: addressing the critical gap in care for SEED/SE-AN, improving better healthcare organization, reducing relapse rates, and lowering costs for this often overlooked patient group.

Hole Appearance Constraint Method in 2D Structural Topology Optimization

A 2D topology optimization algorithm is proposed, which integrates the control of hole shape, hole number, and the minimum scale between holes through the utilization of an appearance target image. The distance between the structure and the appearance target image is defined as the hole appearance constraint. The appearance constraint is organized as inequality constraints to control the performance of the structure in an iterative optimization. Specifically, hole shapes are controlled by matching adaptable equivalent shape templates, the minimum scales between holes are controlled by a hole shrinkage strategy, and the hole number is controlled by a hole number calculation and filling method. Based on the SIMP interpolation topology optimization model, the effectiveness of the proposed method is verified through numerical examples.

Key role of nonprecious oxygen-evolving active site in NiOOH electrocatalysts for oxygen evolution reaction

Nickel-based materials are the most promising electrocatalysts to date for the alkaline oxygen evolution reaction (OER). Identifying the phase transformation in the catalytic process and comparing the theoretical catalytic activity of different crystal facets are important for understanding OER mechanism and rational design. Herein, we calculate the theoretical catalytic activity of the basal plane and edge sites, respectively-two representative configurations in the OER-activate γ-phase NiOOH. DFT theoretical results suggest that the d-band center of Ni site in the basal plane configuration is −2.37 eV, which is closer to Fermi level than that of the edge configuration (−3.02 eV). The above results lead to the stronger adsorption capacity between the metal active sites and the oxygen intermediates. The consequence of Gibbs free energy indicates that the Ni site in the basal plane configuration (0.75 V) has slightly higher theoretical catalytic activity than the edge configuration (0.81 V). The charge density difference and Bader charge analysis results reveal that the hybridization interactions in the basal plane configuration are stronger and have more electron transfer between the surface Ni sites and absorbed OER intermediates. This present study highlights that regulating the optimal electronic structure of metal active site is conductive to high catalytic activity.