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Nejnovější příspěvky

Záznam
Amorphous boron nitride: synthesis, properties and device application
(SPRINGER, 2025-05-02) Sattari-Esfahlan, Seyed Mehdi; Mirzaei, Saeed; Josline, Mukkath Joseph; Moon, Ji-Yun; Hyun, Sang-Hwa; Jang, Houk; Lee, Jae-Hyun
Amorphous boron nitride (a-BN) exhibits remarkable electrical, optical, and chemical properties, alongside robust mechanical stability, making it a compelling material for advanced applications in nanoelectronics and photonics. This review comprehensively examines the unique characteristics of a-BN, emphasizing its electrical and optical attributes, state-of-the-art synthesis techniques, and device applications. Key advancements in low-temperature growth methods for a-BN are highlighted, offering insights into their potential for integration into scalable, CMOS-compatible platforms. Additionally, the review discusses the emerging role of a-BN as a dielectric material in electronic and photonic devices, serving as substrates, encapsulation layers, and gate insulators. Finally, perspectives on future challenges, including defect control, interface engineering, and scalability, are presented, providing a roadmap for realizing the full potential of a-BN in next-generation device technologies.
Záznam
Z3-Noodler 1.3: Shepherding Decision Procedures for Strings with Model Generation
(Springer Verlag, 2025-05-03) Chocholatý, David; Havlena, Vojtěch; Holík, Lukáš; Hranička, Jan; Lengál, Ondřej; Síč, Juraj
Z3-Noodler is a fork of the Z3 SMT solver replacing its string theory implementation with a portfolio of decision procedures and a selection mechanism for choosing among them based on the features of the input formula. In this paper, we give an overview of the used decision procedures, including a novel length-based procedure, and their integration into a robust solver with a good overall performance, as witnessed by Z3-Noodler winning the string division of SMT-COMP'24 by a  large margin. We also extended the solver with a support for model generation, which is essential for the use of the solver in practice.
Záznam
Differentiator circuits with scalable and electronically adjustable time constant and their application in phase shift evaluation
(Elsevier, 2025-05-03) Šotner, Roman; Polák, Ladislav; Petržela, Jiří; Semenov, Dmitrii; Langhammer, Lukáš; Jaikla, Winai
Two novel scalable and electronically adjustable differentiator designs are presented in this paper. These designs are based on special variable gain amplifiers extending well-known concept of standard single operational amplifier-based differentiators. The key novelty lies in their scalability, which allows for an enhanced time constant value by adjusting the ratio of resistors. Simultaneously, the special form of gain control using a DC voltage offers wide electronic tunability. The solution performs high input and low output impedance, both independent of frequency. Experimental testing demonstrated time constant adjustments in two configurations: from 64 ns to 4.5 mu s (a ratio of maximal and minimal value 70) and from 8.7 mu s to 183 mu s (a ratio of 21). As an application example, the proposed differentiator is utilized in the design of a readout system for an absolute phase shift difference to pulse width ratio converter, suitable for monitoring a very slow phenomenon such biosignals.
Záznam
Enhancing Stability of Microwave-Synthesized Cs2SnxTi1-xBr6 Perovskite by Cation Mixing
(WILEY-V C H VERLAG GMBH, 2025-05-05) Reyes-Francis, Emmanuel; Julián-López, Beatriz; Echeverría-Arrondo, Carlos; Rodriguez Pereira, Jhonatan; Esparza, Diego; López-Luke, Tzarara; Espino-Valencia, Jaime; Prochowicz, Daniel; Mora-Sero, Ivan; Turren-Cruz, Silver-Hamill
The double-perovskite material Cs2TiBr6 shows excellent photovoltaic potential, making it a promising alternative to lead-based materials. However, its high susceptibility to degradation in air has raised concerns about its practical application. This study introduces an interesting synthesis approach that significantly enhances the stability of Cs2TiBr6 powder. We implemented a gradual cation exchange process by substituting Ti4+ with Sn4+ in the efficient microwave-assisted synthesis method, developing a double perovskite Cs2SnxTi1-xBr6 type. A systematic study of increasing concentration of Sn4+ in Cs2TiBr6 perovskite has been performed to analyze the effect of Sn-doping degree on the chemical and thermal stability of the material and the optical features in both nitrogen and ambient atmospheres, significantly increasing the stability of the material in the air for over a week. Furthermore, introducing Sn4+ results in a more uniform polygonal crystal morphology of the powders and a slight band gap broadening. We show that microwave-assisted synthesis is highly efficient and cost-effective in producing more sustainable lead-free perovskite materials with enhanced stability and desirable electrical characteristics. This work suggests a promising method for synthesizing perovskite materials, opening new routes for scientific research and applications.
Záznam
Numerical design calculation of flush endplate connections at elevated temperatures
(Ernst & Sohn GmbH, 2025-05-07) Der, Batuhan; Wald, František; Vild, Martin
The fire design of bolted connections is a critical aspect of structural fire engineering, as the failure of steel connections under fire conditions can compromise the entire structure. This paper presents numerical design calculations of flush endplate connections using the component-based finite-element method (CBFEM) at elevated temperatures. The CBFEM models are developed and validated against experimental data, focusing on load-rotation behaviour, connection resistance, and failure modes under thermal stress. By integrating the component method with finite-element analysis, CBFEM provides a robust framework for simulating the behaviour of steel connections in fire. Additionally, the method is verified against Eurocode design specifications for further validation. The results demonstrate that CBFEM is a reliable and accurate approach for the fire design of bolted steel connections at elevated temperatures, offering precise predictions of connection performance and failure mechanisms.