Reliable extraction of the cartridge case after firing is essential to the proper functioning of a gas-operated gun. This study presents a predictive model for the extraction force of a 7.62×39 mm steel cartridge case, based on the maximum chamber pressure and the contact friction coefficient (between the cartridge case and the chamber). A Central Composite Design (CCD) with two factors was used to generate the simulation data from finite element models developed in ANSYS. A reduced quadratic regression model was constructed and statistically validated, showing a high predictive capability (R2 = 0.969, adjusted R2 = 0.953). The model reveals that friction has a stronger influence on the extraction force than the maximum pressure, and that their interaction is non-linear. Experimental validation at the design centre, using a custom-built extraction test rig, yielded an average measured force of 39.10 N, closely matching the predicted value of 38.90 N (error = 0.51 %). The proposed model is a fast and reliable tool for the design and optimisation of ammunition and extractor mechanisms in small arms.

Hyperthermia treatment involves heating tissues to 40–44 °C in order to enhance the efficacy of radiotherapy and/or chemotherapy. Temperature increase is usually induced by the constructive interference of several electromagnetic waves radiating from external sources and can be monitored using magnetic resonance (MR) thermometry. This study aimed to predict temperature increases from non-invasive MR thermometry electromagnetic exposure during deep regional hyperthermia treatment. A 1.5T MR birdcage coil was tuned to produce a homogeneous B1+ field and simulated together with the Sigma Eye hyperthermia applicator and three available patient models. Results show that electromagnetic exposure during MR measurements increases temperature by 0.027 °C, which is, in the hyperthermia temperature range, insignificant. In addition, our results show that the predicted B1+ field homogeneity was influenced by object size and material properties, especially by the water bolus filling the inner part of the applicator.

Despite decades of advancements and research aimed at improving fuel’s physical properties, fretting damage to fuel cladding remains a significant challenge. This study outlines the findings of experiments conducted on Zr-1%Nb alloy coated with protective layers composed of chromium-aluminium (CrAl) compounds and other new perspective materials, such as FeCrAl and CrNi alloys, at the Research Centre Řež. The experiments included debris-fretting tests performed under LWR conditions (320 °C and 15 MPa) and microscopic evaluations of groove depths. The primary goals were: (1) to evaluate the debris-fretting resistance of uncoated Zr-1%Nb samples compared to Zr-1%Nb with coatings and new alloys, and (2) to investigate the potential effects of coatings and new materials on the durability of fuel cladding. The conducted experiments and studies confirmed the benefits of the wear resistance of the ATF types of claddings in comparison to the standard Zr-1%Nb cladding material. Various parameters, such as wire wear and the influence of mutual position of the samples, were considered during the testing to provide the most precise insight into the wear resistance of the tested samples.

We consider a Dirac particle in a spherical box with a time-dependent radius. Analytical and numerical solutions of the time-dependent Dirac equation with time-dependent boundary (Dirichlet) conditions are obtained. Using the obtained solutions, physically observable characteristics of the dynamical confinement, such as the average kinetic energy (as a function of time) and average quantum force acting on the particle by the moving wall, are calculated. The trembling motion is analysed by computing the average coordinate of the Dirac particle as a function of time. The absence of the geometric phase is shown by direct calculation.

Entangled states represent fascinating elements of quantum mechanics and quantum technology. Their generation is an interesting problem combining many techniques developed in quantum optics. Using algebraic properties of special transforms we derive the explicit form of the effective Hamiltonian that enables the generation of highly nonclassical states of the GHZ type. Such Hamiltonians belong to the higher order Hamiltonians often discussed in nonlinear quantum optics. We derive the form of the effective Hamiltonian that enables the generation of highly nonclassical states of the GHZ type.

We review the main research achievements of Miloslav Havl´ıˇcek in algebraic methods in Quantum Theory, his extensive work on realisations of Lie algebras and superalgebras and their representation theory, quantum groups and differential equations.

Water pumping systems are crucial for improving the quality of life for riverside communities. In the Amazon, most of these systems still rely on fossil fuels. However, new off-grid electrification structures using Direct Current Distribution Nanogrids (DCDN) offer better energy efficiency, resilience, cost savings, and reduced environmental impact. This article presents a comparative theoretical and experimental study of various water pumps in Ilha das Onças, Pará, Brazil, where an open structure DCDN with distributed photovoltaic generation and energy storage was implemented to power eight residences and a church. The case study monitored a residential pumping system, analysing the performance before and after installing the DCDN, focusing on various energy supply types (fossil fuel, AC via inverter, and DC connected to the grid), as well as the economic and environmental impacts associated with the energy supply on the island. The results show potential savings of up to $4.5 million in gasoline costs over 25 years, and the equivalent annual CO2 emission can be reduced by 123 tons annually, considering the replicability to other nearby residences, showcasing the benefits of the solution and positive technical, economic, and environmental impacts.

This paper presents an algorithm for evaluating measurement uncertainty at individual points within the Particle Image Velocimetry (PIV) method. The algorithm presents a novel correlation plane metric known as the Loss of Particle Ratio (LPR). This metric is computed by evaluating the magnitude of two correlation peaks: Mutual Information (MI) and the autocorrelation peak. LPR is defined as the ratio of MI, accounting for the total number of particles contributing to signal peak growth, to the magnitude of the autocorrelation peak, which represents the total number of particles within an interrogation area (IA). The computation of LPR allows both the overall measurement accuracy and the accuracy in each direction to be determined. To improve accuracy, the proposed metric undergoes corrections based on the resultant displacement from the last iteration of the Standard Cross-Correlation (SCC) algorithm and the gradient value within the IA. The process of determining the measurement uncertainty relies on the analysis of synthetic data and the application of two tests – the Uniform Flow Test (UFT) and the Couette Flow Test (CFT). The paper explores the impact of individual corrections on the metric and establishes dependencies between the adjusted metric values and measurement uncertainty. The procedure defines the measurement uncertainty based on synthetic test parameterisation, considering key parameters that influence accuracy, such as the density of particles within the IA, the velocity gradient, the particle diameter, the displacement in the last iteration, and the noise level. The synthetic test parametrisation employs various methods for defining the gradient within the IA. The proposed procedure for determining the measurement uncertainty, utilising the corrected metric Loss of Particle Ratio, is compared with an approach based on synthetic test parameterisation for the Standard Cross-Correlation algorithm. The study contributes insights into the effectiveness of the proposed algorithm in assessing measurement uncertainty, offering a comprehensive comparison with existing methodologies.

This work explores the secure data transmission approach to control a robotic arm using Li-Fi technology. Although Li-Fi offers built-in security by keeping the light within the walls of the environment, where it is used, leaks through windows are a concern. The proposed system addresses this concern by using a multi-mode approach with three options: without encryption, Rivest Cipher 4 (RC4) encryption, and Advanced Rivest Cipher 4 (ARC4) encryption. Users can choose the appropriate mode based on data sensitivity and processing constraints. The system transmits the movement commands to the robotic arm via a controller and transmitter. In used encryption modes, the received data is decrypted before instructing the robotic arm to perform the designated action. This secure Li-Fi system offers a promising solution for reliable and secure communication in industrial environments, addressing the limitations of traditional RF communication and improving data security.

A complex adjustable car spoiler opens or closes in dependence on ride properties: the closed state increases negative lift (better for curves), while the open state ensures lower drag (better for straight segments of the road). Both these configurations are studied by using Particle Image Velocimetry method in a wind tunnel at model scale. The three measured planes are perpendicular to the main flow. The wake is characterised by upwind (stronger past the closed variant) and by a pair of wing-tip vortices, although the spoiler wing has no end, it is rounded downwards instead. These vortices are stronger past the closed variant, they migrate towards each other, while their positions correlate by about 30 %. The circulations of both vortices are strongly correlated by about 90 % for the closed case, while this correlations is much smaller (∼25 %) for the open case.