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The application of 3D printing technology in the design of sandwich panels
Get PDFComposite materials including sandwich panels can offer a number of advantages such as excellent strength to mass ratio or stiffness to mass ratio. Sandwich panels can find their application in many industrial sectors where the mass and mechanical properties are critical. Despite these and many other advantages, the use of sandwich panels is associated with many problems, which stem from their structural composition (weak core with high shear stiffness connecting two skins with high in plane stiffness). This composition can cause problems in joining the sandwich panels to each other and to other parts by means of mechanical joints. To solve these problems, there exist many accessories such as inserts. The main objective of this paper is to present the development, manufacturing, and testing of plastic inserts for sandwich panels made by Fused Deposition Modelling 3D printing technology
Comparison of Berkovich and spherical tip indentation for determining the Young’s modulus of polymer thin films encapsulated by a dielectric
Get PDFPixel integrated micro-lenses for CMOS image sensors consist of a stack of polymer acrylate resin films encapsulated by a dielectric layer. Due to the mismatch of thermomechanical properties, adhesive or cohesive fractures can occur. This can lead to reliability issues requiring the knowledge of the polymer thermomechanical properties. Nanoindentation is a standard method for determining Young’s modulus of thin films. However, when performing temperature-dependent nanoindentation studies directly on the polymer film, contamination of the tip can occur near or above the glass transition temperature leading to estimation errors. Therefore, the polymer films must be measured including a protective layer, and a multilayer model is used to extract the polymer’s Young’s modulus. Finite-element simulations of Berkovich and spherical indentations on the complete stack were performed, enabling the identification of a contact radius range within which the relative error resulting from using the multilayer model is less than 10 %. Consequently, room temperature and temperature-dependent tests of the complete stack were performed, enabling the determination of the polymer’s Young’s modulus as a function of temperature without tip contamination
Rock Slope Stability Design
Get PDFThis paper explores the numerical analysis used to determine the global stability Factor of Safety (FS) of the rock slope. The methodology presented herein was employed by the author during the design of the railway cut in Central Bohemia.
Both traditional and numerical methods were applied in designing of the protective stabilization measures for the new rock slope. The analysis supports the results obtained from the conventional geotechnical approach, specifically using the "limit equilibrium method" along the primary planar shear surface, within a rock mass where anisotropic behaviour is influenced by the strikes and dips of discontinuity surfaces, such as bedding planes and schistosity.
The Anisotropic Jointed-Rock Model (AJRM) used in the numerical analysis offers a significant advantage by accounting for the anisotropic behaviour of the rock mass - an aspect often overlooked in standard slope stability methods or when isotropic constitutive models are used in numerical simulations.
Furthermore, mathematical modelling proves beneficial in cases where different constitutive models are required for various geotypes. The combined use of the Jointed-Rock model for the rock mass and the Hardening-Soil model for the quaternary part of the slope within a unified calculation environment provides additional advantages.
The primary objective of the static analysis was to design the rock cut within the geological context of metamorphosed pre-Cambrian rocks, specifically gneiss, located in the southern part of Central Bohemia
PERFUSION INDEX VALUES ARE CONSISTENT ACROSS COMMON LYING SURGICAL POSITIONS
Get PDFPerfusion Index (PI) is an important vital sign in medical practice, with increasing utility in a variety of medical specialties. Its relevance extends to critical care and serves as a valuable measure of anesthetic efficacy. Despite its growing importance, there is a notable lack of literature on the potential impact of different surgical positions on PI measurements. Therefore, this study attempts to fill this gap by investigating whether PI exhibits variance in four different surgical positions: supine, prone, right and left lateral decubitus. The interventional prospective study included 27 volunteers who underwent PI measurement in each position in a randomized order. Using a one-way analysis of variance (ANOVA) for repeated measures, the results showed that at a 5% significance level, no significant differences were found in measured PI values between supine, prone, right and left lateral decubitus positions. Higher standard deviations in the right (±4.46%) and left (±4.58%) lateral decubitus positions indicate greater PI variability than in the supine (±3.91%) and prone (±3.88%) positions. The results suggest consistency of PI measurements across different surgical positions, adding to the knowledge of standardization of PI measurements and interpretation of measured absolute PI values
Comparison of RGB and multispectral cameras for targeted applications in agriculture
Get PDFAgricultural machines nowadays use advanced satellite guidance systems that allow not only autonomous parallel guidance of machinery on the field but also enable the control of agriculture implements based on the geographical location of the field. By using aerial photogrammetry images, it is possible to identify the spots of land that require chemical protection. This information can be used to create prescription maps for the control of specialised implements, allowing the identification of weed outbreaks that require herbicide for their elimination. Using spot-spraying technologies, up to 80% of the active substance can be saved compared to the current common broadcast strategy of applying it to the entire field. This technology automatically controls the sprayer nozzles on the booms only in the spots where it is needed. Using an Unmanned Aerial Vehicle (UAV) allows us to take a detailed picture of the ground. Two main possibilities exist for collecting imagery data with an RGB or multispectral camera. One of the key requirements is the appropriate resolution of the picture, which could be controlled by flying altitude. This paper focuses on comparing RGB and multispectral gathered data toward affected spot identification
Use and access possibilities in the field of training future drivers using a vehicle simulator
Get PDFNovice drivers between the ages of 18 and 24 have a higher risk of accidents, which results from long-term published statistical data. The goal of training at driving schools should be the comprehensive preparation of future drivers for all traffic situations under various weather conditions. Using vehicle simulators allows this practice and training of future drivers, which can be fulfilled and practiced in all weather conditions. Moreover, the vehicle simulator practice can be subsequently (machine) evaluated. Based on the analysis of such driving, complex erudition and readiness of the future driver behavior in real road traffic can be achieved.This article discusses the capabilities of simulator software that can be applied to the education and training of future drivers. The article aims to present possibilities of evaluation software and related practical use in driver education in driving schools. At the end of the article, the expected benefits in the design of the evaluation software for the vehicle simulator are discussed, emphasizing road safety in the education of future drivers
“Smart cities” and their vulnerability
Get PDFIn most discussions, “smart cities” are perceived as a largely positive phenomenon that improves the safety but above all the comfort of its inhabitants. The present paper constructively and critically analyses the approach of de facto unregulated development of “smart cities” with emphasis on the risks associated with this phenomenon. Examples from recent years, not only in the context of developments in Ukraine, show that modern, technological solutions, i.e. e-Government tools, can become a target or even a tool of variously motivated attackers (criminal groups, foreign powers). A “smart” city is often potentially more vulnerable than agglomerations managed more traditionally. This paper aims to demonstrate the possible risks through case studies and determine whether there are more comprehensive theoretical approaches to the subject
Investigating MIDR through AI: a case study of the city of Most in Czech Republic
Get PDFUrban planning, which is inherently multifaceted, requires the development of innovative tools to navigate its complexities. This study introduces a pioneering approach that presents an AI-driven framework tailored for urban data collection and analysis. The impetus for this framework is highlighted through the unique narrative of Most city, which is profoundly transformed by mininginduced displacement and resettlement. While most cities serve as a vivid illustration of the challenges cities can face, especially in the wake of industrial imperatives, this study focuses on the potential of AI in addressing such challenges. The proposed framework, while grounded in advanced computational methodologies, is designed with keen emphasis on real-world applications, ensuring its relevance and adaptability. By integrating Most city’s detailed account with this AI-centric methodology, this study emphasizes the importance of a data-driven approach in understanding and addressing urban dilemmas. Importantly, this study is preparatory, laying the groundwork for the framework’s future application, especially in contexts such as Most city. By bridging advanced AI techniques with tangible urban challenges, this research illuminates a path forward, suggesting a future in which urban planning is not only informed by data but also empowered by AI’s analytical process
STUDY ON CONSTRUCTION MONITORING AND CONTROL OF MULTI-SPAN PRESTRESSED CONCRETE CONTINUOUS BEAM BRIDGE
Get PDFThis article focuses on the construction monitoring and control of a pre-stressed concrete continuous beam bridge, consisting of 13 spans. The goal is to ensure that the bridge structure meets the design requirements throughout the entire construction process. By comparing the theoretical and measured values of the bridge’s alignment and stress during the cantilever construction, closure, and completion phases, it can be observed that the deflection deformation of the bridge is generally in agreement with the theoretical calculations. After the completion of the entire bridge, the measured elevations of each section have an error range of -18mm to 20mm compared to the design elevations, which satisfies the specifications. A comparison analysis of the measured and theoretical stress values at the root and mid-span of the cantilever indicates that the stress difference at the root is within the range of -0.2MPa to 0.2MPa, and the stress differences at the mid-span after completion are 0.03MPa (upper) and 0.09MPa (lower), all of which meet the structural design and code requirements. By establishing a gray GM (1,1) model and using gray system theory, the deflection error during the construction process is predicted and controlled. The prediction accuracy of different methods is compared to determine a reasonable prediction method suitable for long-span pre-stressed continuous beam bridges, providing reference for similar engineering projects
FINITE ELEMENT SIMULATION ANALYSIS OF CURVILINEAR CONTINUOUS BEAM BRIDGE JACKING AND TRANSLATION CONSTRUCTION
Get PDFThis paper investigates the issue of beam misalignment in curved continuous beam bridges. Taking the D0 to D6 spans of the Gongbin Road viaduct as the basis, the main influencing factors causing misalignment in curved beam bridges are analyzed and the causes of transverse and longitudinal misalignment in curved beam bridges are calculated and analyzed using Midas/Civil finite element simulation software. The results indicate that the main influencing factor causing misalignment in the operation of curved continuous beam bridges is the system temperature, with the displacement caused by it being larger than the cumulative displacement caused by self-weight, construction phase, gradient load, vehicle load, and bearing settlement. During operation, the failure of expansion joints changes the boundary conditions of the beam, preventing the bridge from freely expanding and contracting longitudinally under temperature load. As a result, the transverse displacement increases to 2-3 times the normal working state of the expansion joint, leading to beam misalignment