Alan Devoe  Hung Trinh  Fatih Dogan 《International Journal of Applied Ceramic Technology》2023,20(5):3140-3147

The electrical properties of dense, high purity CaZrO₃ discs, sintered at 1380°C with and without added ZrO₂, were investigated up to 950°C. Dielectric constant, loss tangent, and electrical conductivity were measured from 25 to 725°C, and the real and imaginary impedances were measured between 800 and 950°C by impedance spectroscopy techniques. Dielectric constant increased by 8% above 300°C and loss tangent increased from .1% at 25°C to ∼2% above 300°C. Activation energy of electrical conductivity determined between 300°C and 950°C by alternative current (AC) and direct current (DC) measurements. These results indicate that CaZrO₃ could be a useful dielectric material for capacitor applications up to 500°C. A reported decrease in conductivity due to addition of excess ZrO₂ into stoichiometric CaZrO₃ could not be confirmed.  相似文献   

    

Phuoc Tho Dinh  Jeung-Hwan Doh  Sam Fragomeni  Nhat Minh Ho  Tim Peters 《Structural Concrete》2023,24(2):2674-2698

In recent years, the combined use of posttensioning methods with steel decking in the concrete slabs has provided significant benefits in both economic and structural terms. In construction practice, this prestressed composite floor has extensive use in two-way spanning slab systems. However, this application still has inherent limitations due to its novelty and lack of research in this specific field. Hence, this study aims to gain the first insight into the flexural behavior of a two-way posttensioned composite (PTC) slab system based on a numerical approach. Scientific software is utilized for the derived model validation with a focus on models' geometric and material nonlinearity. Available modeling techniques used to perform the posttensioning process and interaction of composite slabs are verified with existing experiments. A comparative study was conducted between PTC slabs and various conventional slab systems on two different support conditions. The findings in this study consider the structural effects of posttensioning and profiled steel sheeting on the flexural behavior of PTC slabs. In addition, numerical results from this research might help structural engineers to modify the design input parameters and make judgments on the bending stiffness of this two-way slab structure. Further studies are required since the shear behavior, flexural, and punching shear conditions in the column regions are not addressed in this article.  相似文献   

    

Ryoichi Furushima  Yutaka Maruyama  Yuki Nakashima  Minh Chu Ngo  Tatsuki Ohji  Manabu Fukushima 《Journal of the American Ceramic Society》2023,106(2):817-821

The fracture toughness of silicon nitride (Si₃N₄) ceramics was evaluated directly from their microstructures via deep learning using convolutional neural network models. Totally 156 data sets containing microstructural images and relative densities were prepared from 45 types of Si₃N₄ samples as input feature quantities (IFQs) and were correlated to the fracture toughness as an objective variable. The data sets were divided into two groups. One was used for training, resulting in the creation of regression models for two kinds of IFQs: the microstructures only and a combination of the microstructures and the relative densities. The other group was used for testing the validity of the created models. As a result, the determination coefficient was approximately 0.8 even when using only the microstructures as the IFQs and was further improved when adding the relative densities. It was revealed that the fracture toughness of Si₃N₄ ceramics was well evaluated from their microstructures.  相似文献   

    

Hoang Trung Trinh  Thi Kim Anh Tran  Shuchi Arora  Suchi Mercy George  Jolitta Sheri  Zhixuan Li  Jae-Hun Yang  Parichart Naruphontjirakul  Kantesh Balani  Ajay Karakoti  Ajayan Vinu 《Advanced Materials Technologies》2023,8(6):2201169

Mesoporous silica-based materials are currently being explored as a new type of bioscaffold for bone regeneration applications. Zinc(Zn) ion incorporation is shown to play an important role in promoting bone regeneration and also providing antimicrobial activity to the scaffold materials. In this work, the role of pore size, geometry, and ordered structure on the Zn loading and release performance of two different mesoporous silica, SBA-1 and SBA-15, are compared. Zn loading is varied from 2.5 to 10 wt% for both samples, and its effect on the antibacterial and osteogenic activity is evaluated. Zn loading up to 10 wt% has a negligible effect on the morphology and textural properties of the mesoporous silica samples. The inductively coupled plasma mass spectrometry (ICP-MS) analysis reveals that SBA-15 exhibits significantly higher Zn release in Luria-Bertani (LB) broth as compared to SBA-1 that is reflected in the higher antibacterial activity of SBA-15 against both gram-positive and gram-negative bacteria. Various assays show that 5 wt% Zn loading is sufficient to produce both bactericidal and inhibitory effects on bacterial cells. The 5 wt% Zn-loaded samples induce osteogenic differentiation ofavianized bone marow-derived stromal cells (TVA-BMSCs) though SBA-15 samples show better compatibility compared to SBA-1, suggesting that Zn incorporation can produce sufficient antibacterial effect and osteogenic differentiation of TVA-BMSCs.  相似文献   

    

Hoang Huy Vu  Nam-Trung Nguyen  Navid Kashaninejad 《Advanced Materials Technologies》2023,8(5):2201836

Superhydrophobic surfaces have many interesting applications because of their self-cleaning, waterproof, anti-biofouling, anti-corrosion, and low-adhesion properties. Accordingly, numerous surfaces with hierarchical micro/nanostructures are designed and engineered to achieve superhydrophobicity. However, these surfaces have two major problems. First, they lose superhydrophobic properties over time, primarily because of environmental conditions such as vibration, external pressure, evaporation, and pollution. Second, most superhydrophobic surfaces fail to repel all types of liquids, especially those with low surface tensions. To address this bottleneck, microstructures with re-entrant curvature have emerged, demonstrating excellent liquid-repellent abilities and robustness. Additionally, microstructures with re-entrant curvature have significant applications in designing surfaces with unidirectional wetting properties for passive liquid handling. Accordingly, this review systematically summarizes the design and fabrication strategies of these re-entrant microstructures. The emphasis is given to wettability studies and other surface properties of re-entrant microstructures and their applications, especially for liquid self-transporting. This paper also highlights the potential applications and remaining technical challenges of fabricating these structures. Finally, the study is concluded by providing the future directions in this promising field.  相似文献   

    

Manh Hung Nguyen  Hoang Vu Dao  Kyoung Kwan Ahn 《国际强度与非线性控制杂志
》2023,33(2):1351-1370

In this paper, a novel robust backstepping control strategy is introduced to achieve high-accuracy tracking performance for electro-hydraulic servo systems (EHSSs) without velocity information in the presence of uncertainties and disturbances. Firstly, system dynamics of the studied EHSS considering parameter deviations, modeling errors, and unknown external loads which are grouped into lumped mismatched and matched disturbances in the mechanical system and pressure dynamics, respectively, are developed. On the basis of the sliding mode theory, two extended sliding mode observers (ESMOs) are originally established to simultaneously estimate the immeasurable angular velocity of the actuator, and lumped mismatched and matched uncertainties. As a consequence, an observer-based controller is designed using the conventional backstepping technique to ensure a highly accurate tracking position control. In addition, the stability of the observer and overall closed-loop control system is conclusively proven through the Lyapunov theory. Finally, several numerical simulations for an EHSS with a hydraulic rotary actuator are conducted to demonstrate the advantage of the recommended method compared to the existing well-known extended state observer-based control approaches.  相似文献   

    

Luong  Ngoc T.  Hoang  Doan 《International Journal of Information Security》2023,22(6):1547-1566

International Journal of Information Security - One of the network performance challenges of Vehicular Ad Hoc Networks (VANET) is the Black Hole attack. This destructive attack severely damages the...  相似文献   

    

Xuan Hien Nguyen;Quang Minh Phan;Ngoc Tan Nguyen;Van Quan Tran; 《Structural Concrete》2024,25(4):2890-2914

The main objective of this paper is to use the data-driven approach to predict and evaluate the mechanical properties of concrete made with recycled concrete aggregate (RCA), including compressive strength and elastic modulus. Using 358 data samples, including 10 input variables, 10 popular machine learning (ML) algorithms are introduced to select the best ML performance model for predicting RCA concrete's compressive strength and elastic modulus. Gradient Boosting and Categorial Boosting have the best performance in predicting the compressive strength of RCA concrete, with R2 = 0.9112, RMSE = 5.3464 MPa, MAE = 4.0845 MPa, and R2 = 0.9175, RMSE = 5.1520 MPa, MAE = 3.7567 MPa, respectively. Light Gradient Boosting and Categorial Boosting have the best performance in predicting the elastic modulus of RCA concrete, with R2 = 0.8775, RMSE = 2.3560 GPa, MAE = 1.8330 GPa, and R2 = 0.9300, RMSE = 2.3560 MPa, MAE = 1.2589 MPa, respectively. Based on the Shapley Additive Explanation analysis, the influence of main factors on compressive strength and elastic modulus of RCA concrete values has been analyzed qualitatively and quantitatively. RCA replacement level and cement/sand ratio slightly affect compressive strength but have a dominant influence on the elastic modulus of RCA concrete.  相似文献   

    

Muhammad Talal Ali Khan  Haisu Li  Nathan Nam Minh Duong  Andrea Blanco-Redondo  Shaghik Atakaramians 《Advanced Materials Technologies》2021,6(7):2100252

Compact and robust waveguide chips are crucial for new integrated terahertz (THz) applications, such as high-speed interconnections between processors and broadband short-range wireless communications. Progress on topological photonic crystals shows potential to improve integrated terahertz systems that suffer from high losses around sharp bends. Robust terahertz topological transport through sharp bends on a silicon chip has recently been reported over a relatively narrow bandwidth. Here, the experimental demonstration of topological terahertz planar air-channel metallic waveguides, which are able to integrate functional components inside the chip, is reported. This platform is fabricated by a simple, cost-effective technique combining 3D-printing and gold sputtering. The relative size of the measured topological bandgap is ≈12.5%, which entails significant improvement (≈60%) over all-silicon terahertz topological waveguides (≈7.8%). Robust THz propagation around defects and delay lines is further demonstrated. This work provides a promising path toward compact integrated terahertz devices as a next frontier for advanced terahertz systems such as wireless communications.  相似文献   

    

Phuocthoi Hoang;Zhenxin Zhang;Jinyuan Ren;Yao Peng;Jinzhen Cao; 《Polymer Composites》2024,45(11):10349-10364

In this study, three types of biochar including wood biochar (WB), rice husk biochar (RHB), and bamboo biochar (BB) were used as fillers to mix with wood flour (WF), polypropylene (PP), and maleic anhydride polypropylene (MAPP) to prepare wood polymer biochar composites (WPBC). The influences of biochar types and addition amounts (10 wt%, 20 wt%, 30 wt%, and 40 wt%) on the mechanical properties, dimension stability, and thermal stability of WPBC were investigated. The results showed that the water absorption rate and thickness swelling rate of WPBC were lower than control group due to the hydrophobic nature of the biochar. Additionally, the presence of biochar was beneficial to the interfacial bonding and stress transmission in composites, resulting in better mechanical properties. Composites containing 20 wt% RHB showed the highest flexural modulus among all, which increased by 11.27% compared to control group. Adding WB also enhanced the tensile and impact strength of composites at a loading level of 10 wt%, with the value of 39.10 MPa and 15.55 KJ/m2, respectively. The thermal stability and flame retardancy of WPBC was improved due to the presence of SiO2 in biochar, which could hinder heat transmission and thermal degradation during combustion process. Concurrently, the rate of heat release and smoke generation in WPBC also decreased significantly. The oxygen limiting index (LOI) of composites with 20 wt% RHB was as high as 26.64%, increasing by 30.14% compared to control group. The results suggested that biochar was a promising alternative to commercial additives for the cost-effective production of composites.  相似文献