CTU Open Journal Systems (Czech Technical University, Prague / České vysoké učení technické v Praze)
Not a member yet
4735 research outputs found
Sort by
Exact solutions for time-dependent complex symmetric potential well
Get PDFUsing the pseudo-invariant operator method, we investigate the model of a particle with a time-dependent mass in a complex time-dependent symmetric potential well V (x, t) = if (t) |x|. The problem is exactly solvable and the analytic expressions of the Schrödinger wavefunctions are given in terms of the Airy function. Indeed, with an appropriate choice of the time-dependent metric operators and the unitary transformations, for each region, the two corresponding pseudo-Hermitian invariants transform into a well-known time-independent Hermitian invariant which is the Hamiltonian of a particle confined in a symmetric linear potential well. The eigenfunctions of the last invariant are the Airy functions. Then, the phases obtained are real for both regions and the general solution to the problem is deduced
STUDY ON REMOTE INTELLIGENT MONITORING SYSTEM OF SLOPE BASED ON SARMA ALGORITHM AND ARCGIS
Get PDFFirstly, a typical slope on Liu-An highway was selected as the research object. Then, based on the Sarma algorithm and considering the influence factors such as inhomogeneous boundary conditions, water content and reinforcement Angle, A slope stability analysis system based on the improved Sarma algorithm is developed to build an engineering geological model and a remote intelligent monitoring system platform for the slope. On this basis, we select the slope of typical road sections for remote monitoring and pre-warning. ArcGIS technology is used to carry out difference analysis of monitoring data, realize GIS 3D visualization, and verify the 3D visualization monitoring effect of the system. The results show that the system is stable and reliable. The range and precision meet the specification requirements, and can effectively realize the 3D visualization monitoring of highway slope. It can also realize four-level pre-warning, which lays a foundation for the long-term safe operation of highway
The influence of modern headlamps on the recognition of portable traffic signs and warning triangles
Get PDFThis article focuses on the issue of portable traffic signs and their visibility using different light sources such as halogen, Xenon, or LED. The measured values of luminance and retroreflection for each object are used to distinguish the individual results. The results show the differences between the various light sources on the visibility of the measured objects. Furthermore, from these results it is possible to evaluate portable traffic signs regarding degradation due to mechanical wear or aging
Segmentation of pores in carbon fiber reinforced polymers using the U-Net convolutional neural network
Get PDFThis study demonstrates the utilization of deep learning techniques for binary semantic segmentation of pores in carbon fiber reinforced polymers (CFRP) using X-ray computed tomography (XCT) datasets. The proposed workflow is designed to generate efficient segmentation models with reasonable execution time, applicable even for users using consumer-grade GPU systems. First, U-Net, a convolutional neural network, is modified to handle the segmentation of XCT datasets. In the second step, suitable hyperparameters are determined through a parameter analysis (hyperparameter tuning), and the parameter set with the best result was used for the final training. In the final step, we report on our efforts of implementing the testing stage in open_iA, which allows users to segment datasets with the fully trained model within reasonable time. The model performs well on datasets with both high and low resolution, and even works reasonably for barely visible pores with different shapes and size. In our experiments, we could show that U-Net is suitable for pore segmentation. Despite being trained on a limited number of datasets, it exhibits a satisfactory level of prediction accuracy
Influence of Oxygen-containing Filling Gas Mixtures on the Interruption Capability of MV Load Break Switches
Get PDFNowadays SF6 is commonly used as filling gas for medium voltage load break switches due to its outstanding insulating and arc-quenching properties. However, due to its high global warming potential the interrupting performance of alternative eco-friendly gases are investigated for such devices. This contribution investigates the thermal interruption capability of a medium voltage load break switch using two different oxygen-containing gas mixtures: dry air and a mixture of nitrogen, oxygen and carbon dioxide. The findings indicate an improved performance in comparison to pure nitrogen when considering an admixture of oxygen. In gas mixtures containing 80\% nitrogen, the addition of oxygen results in an enhanced thermal interruption capability compared to an equivalent proportion of carbon dioxide
Thermal Current Interruption Performance of CO2 and CO2/C4F7N mixture
Get PDFThis contribution aims to compare the thermal interruption performance of pure CO2with a mixture of CO2/C4F7N. Measurements primarily show higher interrupting capability for amixture with C4F7N. Detailed analysis shows a distinct difference in the failure mechanism which forCO2/C4F7N is thermal failure and for CO2 mostly “hot dielectric” failure. The difference in the failuremechanism is relevant for the test duties with the most severe TRV. The influence of ablated nozzlematerial on the interruption process can be ruled out
Possibilities of complex numerical modelling at the Czech Geotechnical Society workplace
Get PDFIn the paper, there are examples of complex geotechnical problems in both 2D and 3D that are modelled using PLAXIS software on the specialist workstation provided by the Czech Geotechnical Society to their members
Using of modern technologies for visualization of cultural heritage
Get PDFThis paper explores the historical evolution and contemporary applications of photogrammetry and laser scanning in cultural heritage preservation, focusing on the restoration of the Shush synagogue in Iraqi Kurdistan. It traces the development of documentation techniques, highlighting photogrammetry\u27s pivotal role and the impact of the digital revolution. The case study of Project Shush illustrates the practical use of geomatics techniques, advanced 3D modeling, and collaboration with NGOs and authorities. The methodology outlines the use of technologies like terrestrial laser scanners (BLK360, Zeb-Revo) and UAVs, emphasizing their mobility and accuracy. Results detail the project stages, showcasing the creation of a detailed 3D model and the use of Unreal Engine for visualization. The conclusion emphasizes the importance of 3D documentation in cultural heritage and celebrates the success of the Shush synagogue restoration as a testament to technological advancements in preservation. Our research has shown that the joining of different 3D object documentation technologies significantly improves the quality and speeds up the workflow. Comparison of partial point clouds in software Cloudcompare on a case study of a smaller historic building showed differences in the internal structure in centimeters, while for the external parts that were covered with vegetation the differences reached up to decimeters
Application of an artificial intelligence segmentation for deep hyperthermia treatment planning in the pelvic region
Get PDFDuring a microwave hyperthermia oncology treatment, the target region temperature is elevated to the temperatures of 40–44 °C, which improves the therapeutic effect of a standard radiotherapy and/or chemotherapy treatments. Amplitudes and phases of antenna input signals in the phased array setup surrounding the 3D patient model are optimised with respect to maximise the energy deposition in the target region. In this study, we successfully integrated an automatic artificial intelligence segmentation routine, used for patient-specific 3D model generation, into the hyperthermia treatment planning process. This allows us to apply more realistic patient 3D model for the online hyperthermia guidance including detailed retrospective analyses of the overall treatment quality, possibly leading to a widespread clinical use of the hyperthermia treatment planning
Enhancement of power transfer capacity of transmission network using multilevel multifunction inverter
Get PDFThis article presents a multilevel multifunction inverter (MLMFI) with a novel controller for the grid-connection of a solar array. The aim of this work is to improve the technology of the power transfer capacity of existing transmission lines in order to alleviate the current energy crisis. An effective mathematical modelling of an MLMFI configuration having two series-connected H-bridges per phase with isolated solar arrays is presented. A novel closed-loop controller is proposed for reference signal generation using the PWM technique. With the proposed controller, the power flow in a transmission line is analysed for daytime and nighttime conditions. The proposed controller performance was tested on a realistic single-machine infinite-bus power system with midpoint MLMFI using MATLAB simulation software. The proposed MLMFI-based solar array enhanced the stable power transfer limit of a transmission line. A comparative analysis between conventional and proposed controllers for power flow and transient stability studies was also presented. The proposed MLMFI results were validated by developing an experimental model