Journal of Engineering and Thermal Sciences
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Dominator Coloring of Total Graph of Path and Cycle
Get PDFA dominator coloring of a graph G is a proper coloring in which every vertex of G dominates every vertex of at least one-color class possibly its own class and each color class is dominated by at least one vertex. The minimum number of colors required for dominator coloring of G is called the dominator chromatic number of G and is denoted by χdG. In this paper, we have established the relation between dominator chromatic number χdG, chromatic number χG and domination number γG. We have investigated results on total graphs of path and cycle with χdG = χ G + γ G and χdG = χ G + γ G - 1
Mechanical behavior of a highway tunnel under the influence of lining crack disease
Get PDFHighway tunnels built in China in the early years of operation have different forms of diseases, which have a great impact and threat to the normal operation and safety of the tunnel. To ensure the safety and stability of the lining structure, this paper analyzes the mechanical behavior of the lining structure under the influence of the disease and reveals the evolution law of the lining crack disease for typical tunnel lining cracks. The results of the study show that only the circumferential and longitudinal stresses at the vault increase when cracks exist in the inner wall of the lining vault. The longitudinal cracks in the inner wall of the lining have the greatest influence on the lining stress state
Diagnosis of rotating machinery based on improved convolutional neural networks with gray-level transformation
Get PDFA fault diagnosis method for the rotating machinery based on improved Convolutional Neural Network (CNN) with Gray-Level Transformation (GLT) is proposed to increase the accuracy of the recognition adopting the multiple sensors. The Symmetrized Dot Pattern (SDP) in this method is applied to fuse the data of the multiple sensors, and the multi-color value method is adopted to increase the feature dimension. The grayscale and GLT are used to reduce the dimension of the SDP image. The SDP grayscale image is finally input to the CNN network for training recognition. The research results show that the diagnosis accuracy of the rolling bearing system based on the novel method is up to 98.6 %. Compared with the method without the multi-color value and GLT, the recognition accuracy of the proposed method is improved by 22.3 %, and the training time is reduced by about one third. The research work reveals that the developed method has the potential application value under the multi-sensor working conditions for the fault diagnosis
Full-scale shaking table test on seismic performance of a steel frame with translational-type precast-concrete exterior wall panel
Get PDFIn order to investigate the deformation behavior, mechanical characteristics of connections, and failure mode of translational precast concrete wall-panels under earthquake loading, a full-scale two-story steel frame model was designed. This test model consisted of 12 precast concrete wall-panels connected with fixed connections at the bottom end and translational-type connections at the top end. This model passed the shaking table testing, and the results demonstrate that the translational-type precast concrete exterior wall panel can ensure the sufficient relative displacement between the wall panel and the main structure under large earthquake loads. It has sufficient capacity to adapt the deformation between the main structure and the wall panels. During the test, localized cracking was observed on the wall panel, while all connections remained in elastic state. The connections between precast concrete exterior wall panels exhibited good performance, that indicates it is an effective tool to protect frame building hangings with exterior wall panels under strong earthquake events
Utilizing a knowledge-based training algorithm and time-domain extraction for pattern recognition in cylindrical features through vibration and sound signals
Get PDFThis study presents a new solution to address challenges encountered in additive manufacturing, specifically in the context of 3D printing, where failures can occur due to complications associated with the nozzle or filament. The proposed solution in this research involves using a time-domain feature extraction method that leverages sound and vibration patterns. By implementing sensors to capture these signals in a controlled and noise-free environment, and then utilizing a Multi-Layer Perceptron (MLP) model trained accurately to predict upcoming signals and vibrations, proactive anticipation of printing outcomes is facilitated, including potential failures. Simulation results obtained using MATLAB for the MLP showcase the effectiveness of this approach, demonstrating remarkably low error rates. Furthermore, through rigorous data validation, the proposed method's ability to accurately identify sound and vibration signals is confirmed. As a result, the likelihood of failures is significantly reduced, thereby preventing defects in the filament. The implications of this solution hold great promise in substantially enhancing the reliability and efficiency of additive manufacturing processes
Static transmission error measurement of various gear-shaft systems by finite element analysis
Get PDFTransmission error (TE) is a significant parameter related to gears vibration widely investigated by many authors using different approaches. However, in previous studies, spur and helical gears were mainly examined. There is a lack of studies addressed to double helical and herringbone gears and a comparison among several types of gearing with parallel axes. In this paper, spur, helical, double helical, and herringbone gears are analyzed in terms of static transmission error (STE), contact pressure and tooth root stress. Static contact analyses were conducted using the finite element method (FEM) which is often considered a tool for validating other methods and approaches. Moreover, three variants of boundary conditions of each gear type are introduced, including flexible shafts and the effect of a tip relief modification at sole gears, without shafts, was analyzed. In addition, a concept of a compact test rig intended for STE measurements at low loads was presented. The results have shown, among other things, significant influence of the shaft stiffness and boundary conditions on meshing characteristics
Studying the impact of reservoir temperature, water salinity and CO2 dryness on CO2 injectivity during geological CO2 sequestration
Get PDFCarbon capture and storage (CCS) is proved to be effective measure for reducing CO2 emissions. whilst the world still highly depends on the use of fossil fuel energy, this method is necessary for reaching the world’s 1.5 °C goal. Saline aquifers among all possible underground formations are most common targeted ones for CO2 storage due to their frequent presence, and large storage capacity. However, this storage option suffers from sufficient well injectivity to inject large volumes of CO2 at acceptable rates through a minimum number of wells. The injectivity impairment/reinforcement happens through mineral dissolution, fine particle movement, salt precipitation and hydrate formation (known so far). Each of these mechanisms will be more dominant in injectivity alteration at different distance from the injection point depending on reservoir pressure and temperature, formation water salinity, rock mineralogy, and flow rate of CO2 injection as well as its dryness. In this study we have chosen a commercial software Eclipse 300 together with an open-source code to investigate the impact of formation characteristics, CO2 -Brine-Rock interaction, pressure, temperature as well as injection rate on injectivity alteration. The goal for this work is to provide a workflow which can help predicting injectivity alteration using the existing tools. Simulation results show that permeability is affected severely by salt precipitation during CO2 injection. Combined static and dynamic parameter study demonstrate that the injection rate plays a crucial role in size and expansion of CO2 plume as well as growth rate of dry out zone length, amount of salt precipitation and length of equilibrium region. The higher the injection rate, the quicker activation of the capillary and gravity force which leads to drag more brine to near well-bore resulting in higher volume fraction of salt precipitation. However, low injection rate could result in smaller CO2 plume, shorter dry out zone and longer equilibrium region in term of distance from injection point. Thus, optimizing the injection rate regarding reservoir parameters i.e., temperature, pressure and in-situ salinity, will lead to higher storage capacity as well as well performance and maintenance
Uncertainty analysis for cylindrical structure vibration according to generalized polynomial chaos method
Get PDFAiming to gain an accurate prediction model of the vibro-acoustic problem for the vibrating structure systems, the uncertainty vibration analysis for the cylindrical shell structure considering construction factors is investigated. The generalized polynomial chaos (GPC) method is used to gain the analytical solution of the free vibration for the cylindrical shell structure, in which the construction uncertainty factors, comprising the material uncertainty parameter and construction geometric uncertainty parameter, are considered. By combining the collocation method and generalized polynomial chaos method, the influence of the uncertainty construction factor on the free vibration properties for the cylindrical shell structure is verified by a numerical analysis. The results provide technical support for the design and construction of the vibrating structure for vibration and noise reducing
Internal risk assessment of whole process engineering consulting consortium based on GRA-TOPSIS-FMEA
Get PDFIn order to select key risk factors, effectively control risks, and promote the smooth development of the whole process of engineering consulting consortium, Based on WBS-RBS risk identification in the whole process of engineering consulting, this paper introduces FMEA model, applies rough set and binary semantics to evaluate risk from multiple dimensions of occurrence, severity and difficulty to detect, and uses G1-improved CRITIC to calculate the comprehensive weight of risk evaluation factors, and then severity is revised based on DEMATEL. The GRA-TOPSIS model is constructed for risk ranking. Finally, the model is applied to a road network project and the analysis shows that communication and coordination risk, termination risk and schedule risk are the key risks. The model is suitable for risk assessment in the joint body and provides a feasible method for risk control in the whole process of engineering consulting consortia
Development of a method for online control of plastic deformations of a tank wall and assessment of its residual life
Get PDFA method of operational control of the residual resource of the tank is proposed. As a tool, the measurement of deformations of the tank wall, the assessment of plastic deformations are used. To determine the deformation, it is proposed to use a light guide installed on the wall, with the help of which the change in the curvature of the wall is measured. A device prototype containing a light guide and the necessary electronics has been developed, and the dependence of the device readings on the curvature of the light guide has been experimentally determined. The simulation of the tank in the computer simulation program was carried out in order to compare the integral of the relative deformation over the height of the tank with the readings of the device. An algorithm for processing measurements of device readings and estimating the residual life of the tank is proposed