Journal of Engineering and Thermal Sciences
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Vibration influence of different types of heavy-duty trucks on road surface damage
Get PDFUnder the interaction of the wheels of heavy-duty trucks on the random road surface when the vehicles are travelling, their generated vibrations not only affect the driver's ride comfort but also impact the road surface damage. To assess the vibration influence of different types of vehicles on the road surface damage, three dynamic models of the two axle, three axle, and four axle of heavy trucks have been build and computed via the Matlab/Simulink software. The dynamic tire load, dynamic load coefficient, and dynamic load-stress factor are chosen to assess the friendly load of different heavy trucks under the different operating conditions of the vehicle. The obtained result indicates that the dynamics parameters including suspension system, tires, and axle load distributions of heavy trucks have a greater effect on the dynamic tire force than the total weight of the vehicle. In order to ensure the road’s safety, the traffic management should intervene quickly to give a velocity limit for vehicles under the condition of the vehicle moving with the empty loaded on the poor road surface
Vibration-collision mechanism of dual-stabilizer bottom hole assembly system in vertical wellbore trajectory
Get PDFThe lateral vibration of drill string causes well deviation and the collision between drill collar and sidewall, and severe lateral vibration even affects the drilling safety or reliability. In view of the problems above, the lateral vibration characteristics of drill string need to be analyzed. Therefore, a newly vibration-collision model of BHA (bottom hole assembly) with random collision characteristics is proposed in this paper. Firstly, the dynamic model of drill collar with double stabilizer is presented by utilizing the Lagrange equations. Secondly, the dynamic characteristics of drill collar in air and mud drilling is analyzed with different collision frequencies. Subsequently, the displacement and motion trajectory of drill collar under different structure parameters of BHA and mechanical parameters of system are investigated by numerical simulation. Finally, the influence of rotation speed of BHA and length of drill collar on lateral vibration of drill collar is discussed. The results indicate that the lateral vibration of drill collar in air drilling is more serious than that in mud drilling; and the higher the collision frequency, the more severe the lateral vibration. Improving rotation speed of BHA, length of drill collar and WOB (weight on bit) have promoting influence on lateral vibration of drill collar; however, increasing stabilizer diameter has suppressing influence on lateral vibration of drill collar. The research findings give reasonable guidance for structure design of BHA and selection of mechanical parameters of system
Determination of reasonable parameters for skew bridge under different skew angles
Get PDFA finite element model is created using OpenSees software to perform a time history analysis in order to analyze the seismic response law of a skew bridge and the damage volume of its key components, using a typical 3×20 m skew continuous girder bridge as an example. The seismic response of the skew continuous girder bridge under various factors such as the size of the abutment expansion joint, shear key gap, and shear key strength is studied then the damage rate is assessed for the bearing, shear key, and pier. The research results show that under the action of earthquake ground motion with 0.3 g PGA, the seismic force transmitted to the pier is small, and the pier is elastic owing to the sliding of the bearing, but the damage degree of the shear key is larger than that of the bearing and pier. The impact increases the rotation effect of the main beam in the direction of off acute angle, resulting in a greater damage to the shear key at the acute angle than that at the obtuse angle. The damage of bearing and shear key increases and then decreases with the increasing of expansion joint, and the larger the skew angle is, the smaller the expansion joint will be corresponding to the maximum displacement of bearing and shear key. With the increase of the shear key gap, the deformation limitation effect of the shear key on the main beam decreases significantly, resulting in a linear increase in the bearing slip, which increases the risk of the main beam subsidence. With the increase of the shear key strength, the bearing and shear key damage decreases greatly at first, and then increases slightly. However, the pier damage increases obviously. In an area with a high risk of earthquake, it is recommended that the shear key can be a “fuse element”. For any oblique angle, the shear key gap can be reduced to 2 cm, and the shear key strength can be increased to 125 % or 150 %. When the skew angle is between 30 and 60, the expansion joint size can be increased to 12 cm or 16 cm
Align MWCNT/GNPs/PDMS based nanocomposite dry ECG electrodes for ECG recordings
Get PDFThis work focuses on the fabrication and testing of highly conductive polymer electrodes to measure the biomedical signals known as an Electrocardiogram (ECG). When doing this, optimal skin contact is considered. Align Multiwalled Carbon Nanotubes (AMWCNT), Graphene Nanoplates (GNPs), and Polydimethylsiloxane (PDMS) were used to fabricate the electrodes for continuous ECG monitoring. Sonication and magnetic stirring were used to disperse the mixture. The conductance of the PDMS/GNPs/AMWCNT electrodes were measured using a digital multimeter and were compared with that of standard silver-silver chloride (Ag/AgCl) electrodes. The current study showed that real-time monitoring achieved by an internet of things (IoT) systems with microcontroller
A reduced chemical kinetic mechanism of diesel fuel for HCCI engines
Get PDFA reduced mechanism of diesel fuel was developed on the basis of Wang’s mechanism. First, for removing the unimportant reactions, an importance index was defined on the basis of computational singular perturbation (CSP). Choosing the importance index of 0.0065, the 140 unimportant reactions were removed, and obtained a smaller mechanism of 403 elementary reactions. Second, 32 global quasi-steady-state (QSS) species were found with the threshold value of 0.005. Finally, the smallest mechanism containing 77-species was obtained. By contrast with the ignition delay time of the original Wang’s mechanism, the maximum error of the final 77-species mechanism was 7.2 %. The final mechanism was also performed with the original Wang’s mechanism and the experiments date from the selected homogeneous charge compression ignition (HCCI) engine, the good overlap of curves was obtained and the maximum error of the simulation results was less than 10 %
Challenges and opportunities for enhanced patient care with mobile robots in healthcare
Get PDFMobile robots are being used more frequently in healthcare environments to tackle a variety of issues, such as patient monitoring, drug administration, and support for healthcare professionals. However, considering how nascent the topic of deploying mobile robots in healthcare is, there hasn’t been much investigation into the potential benefits and drawbacks of doing so. The goal of this research study is to examine the current state of mobile robots in healthcare, the opportunities they present for enhancing patient care, and the difficulties that must be solved to take advantage of these advantages, including safety concerns, dependability and accuracy issues, and cost effectiveness issues. We identify critical elements that support the successful integration of mobile robots into healthcare environments, as well as potential drawbacks and ethical concerns such as patient privacy, informed consent, autonomy, and accountability related to their use, through a systematic review of the literature of mobile robot implementations in healthcare. Our results show the potential of mobile robots to enhance patient care by delivering more effective and efficient healthcare services, but they also emphasize the need for additional research and development to overcome the difficulties in integrating these robots into healthcare workflows. In the end, this research intends to provide a basis for future research and development in this fascinating and quickly developing sector, as well as to contribute to a better understanding of the opportunities and constraints connected with the use of mobile robots in healthcare
Plane waves in an isotropic thermoelastic diffusive material using strain gradient theory
Get PDFThe governing equations of motion for an isotropic strain-gradient thermoelastic material with diffusion are formulated in context of Lord and Shulman generalization of thermoelasticity and are further specialised for a two dimensional plane. Plane harmonic solution of the governing equations in two-dimension suggests the existence of five plane waves which include four coupled longitudinal waves and a shear vertical wave. A numerical example is considered to illustrate graphically the effect of frequency, measure constant of diffusion, measure constant of thermo-diffusion, thermal relaxation time, diffusive relaxation time and the coefficients of hyperstress tensor on the phase speed and attenuation coefficients of the plane waves
Temperature and humidity sensor monitoring of directly buried cable based on temperature field distribution simulation of power cable
Get PDFPower cable is a piece of major transmission equipment, and its operating temperature as a major factor determines whether the cable system can operate safely and reliably and the current-carrying capacity. Therefore, it is of great significance to master the real-time temperature and the distribution of the power cable core. During the aging of cable insulation, temperature, as a major factor, directly determines the aging rate. One of the basic parameters on the power cable is the ampacity. If the ampacity is high, the cable will be overloaded. In this paper, the thermal circuit method is used to construct and calculate the cable, and the whale algorithm is used to estimate the temperature of the cable conductor. The conductor is estimated accurately within the allowable error range. The results are compared with the results of finite element simulation to verify the effectiveness of the finite element method. Through the experimental analysis, the model is established according to the cable trench on the spot. The steady-state temperature field is calculated through parameter setting. The average packet loss rate is 0.066 %, and the relative error is 0.32 %, which proves that this study can optimize the communication mode of the network and achieve a better monitoring effect. The method realizes the real-time temperature rise prediction of the cable core conductor by using the temperature rise of the outer skin. It can provide a certain theoretical basis for the online monitoring and engineering practical application of the cable core temperature and has practical significance
Sensitive analysis on added damping of shunted piezoceramic damping: cantilever and simply supported beam
Get PDFThe current research investigates the prediction of piezoelectric damping of resistively shunted beams caused by resistors via joule heating. In order to maximize the extra damping of the piezoelectric shunted beam system, a sensitivity analysis was done. The geometrical impacts on the maximum additional damping simulation are investigated for different length and thickness ratios with the position of the PZT-5H from the base of the cantilever and simply supported beams. Prior to doing sensitivity analysis, a mathematical model for estimating extra damping from voltage produced. Validation experiments are also carried out
A review on different regulation for the measurement of transport noise and vibration
Get PDFTransport noise and vibration have a negative influence on the environment, human health, and quality of life. The measurement and analysis of transport noise and vibration are required by the regulations and guidelines that various countries have set in order to manage and mitigate these effects. This review paper provides an overview of the requirements for the measurement and analysis of vibration and noise in transportation in different countries. The paper examines the measurement and analysis parameters, methods, and standards used in the United States, Europe, Australia and Japan. The review finds that although the requirements for measurement and analysis vary between countries, there are common parameters and methods used worldwide, such as sound pressure level and frequency spectrum measurements, noise and vibration impact assessment, prediction, and control measures. A comprehensive understanding of the measurement and analysis requirements for transport noise and vibration in different countries is essential for ensuring compliance with regulations, mitigating adverse impacts, and promoting sustainable transport development