Maintenance, Reliability and Condition Monitoring
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Analysis and optimization of abnormal noise in lubricating oil circuit of diesel engine
Get PDFEngine abnormal noise is one of the common engine faults, which will affect the comfort, power and safety of the automobile at the same time. In order to study the abnormal noise existing in the test process of diesel engine lubricating oil circuit system, 1D numerical simulation analysis of its flow field is carried out by using simulation software GT-power to verify the boundary conditions of the model and analyze the fluctuation of pressure at different speeds and temperatures. Through numerical analysis, it is found that there is almost no pressure fluctuation in the lubrication system before the pressure limiting valve is opened, but after the pressure limiting valve is opened, pressure fluctuation occurs in the pipeline, and the pressure fluctuation is different at different positions. Finally, the lubrication pipeline is simulated and analyzed by Pumplinx software, and the pressure fluctuation in the lubrication pipeline of diesel engine is reduced by optimizing the diameter of the oil pipeline and increasing the cavity structure
Preparation and properties of polyamide elastomers by a new synthesis route of Michael addition reaction
Get PDFAt present, the mainstream industrial synthesis method of polyamide is still bulk fusion polymerization, which is not in line with the concept of green synthesis because of the high threshold of reaction conditions and large energy consumption. Based on this, a new synthesis route of polyamide elastomer was studied in this paper. By synthesizing the end-functionalized long carbon chain diacrylamide (DDA) containing amide bonds, the synthesis mechanism was made by the thiol double bond Michael addition reaction. A series of polyamide elastomers with different ratios of hard and soft segments were synthesized by using dimercaptan chain extenders with different molecular weights. The results showed that the new synthesis route successfully prepared DDA and polyamide elastomers. The mechanical properties of the products were excellent, and the strain rate could reach 383 %. Tensile strength up to 23.08 MPa. The synthesis route has the characteristics of simple reaction process, mild reaction conditions and high reaction conversion rate. It provides theoretical guidance for the new synthesis route of polyamide elastomer
Reliability analysis of cable crimping terminals with different applicator tools
Get PDFThis study provides a comprehensive evaluation of the stability of crimping of the same terminal on FLRY A cables using three different applicators. The research involved conducting pull tests on 50 samples for each applicator type, analyzing the results using Minitab software to assess the consistency and strength of the crimp connections. The findings indicate that while the Demirel applicator produces the highest average pull test values, the Tyco applicator demonstrates superior consistency, making it more suitable for applications where process stability is critical
Structural design and dynamic characteristic analysis of adjustable badminton serving machine
Get PDFSystem dynamics serves as a crucial foundation for evaluating the performance of mechanical auxiliary equipment. To enhance the stability and reliability of the badminton launch process, structural design and dynamic analysis were conducted on a mode-adjustable, precise control badminton serving mechanism. The combination of eccentric crank-slider mechanism, stretched springs, and electromagnets was used in mechanical structures, which could effectively effectively improve the smoothness of the badminton in the launching process. The virtual prototype of badminton serving machine was established and imported into ADAMS for dynamic simulation analysis, verifying the correctness of the serving and retrieving mechanisms. Using the aerodynamic equations, the trajectory of badminton movement under different working parameters was simulated and analyzed. The dynamic analysis results show that the design of the launching and catching mechanisms is scientific and effective. The launch angle and initial velocity are the key factors that determine the trajectory of the badminton
Vector analysis of unmanned aircraft sea surface imaging characterization based on ISAR
Get PDFUtilization of airborne Inverse-Synthetic-Aperture-Radar (ISAR) for detection of moving targets on the sea surface is studied in this paper. In order to systematically analyze the characterization of radar imaging in the presence of both motion and observation uncertainty of a target, this study incorporates the Bayes-PRM multi-query algorithm for fusing ISAR multi-sensing information. The algorithm isochronously samples the physical quantities, such as UAV position, altitude, pitch angle, and velocity as a sequence of multivariate groups, and converts the time-series data of the trajectories into distributional features in graph theory. The coupled edge weights and Alternating Direction Method of Multipliers (ADMM) are introduced through the coupling framework combined with the ambient graph. With ADMM, the quadratic penalty term is used to achieve a simple linear function, and subproblems involving amplitude, linear velocity, and yaw angle can be embedded in a sequential solution scheme. The quality of the primal and dual solutions is then improved in an iterative manner to achieve vector analysis of the UAV. The potential maneuvering region of the target is fitted to a Gaussian-Wiener stochastic movement model, which in turn yields the detection expectation through point set coverage. By analyzing the tracking simulation results and diffraction theory, the experimental results are transformed into a function of the UAV multi-vector, and the angular linearization model of the multi-vector under the radar image is developed, which solves the optimal elevation angle and the optimal path for the maximum scanning radius of the airborne radar. The nominal trajectory of the UAV is effectively obtained, which confirms the improvement of the credibility of ISAR in target detecting. Through the proposed model, the results of object detection accuracy were improved
Design of treatment scheme and identification method of treatment effect for soft soil subgrade
Get PDFAccording to the characteristics of the soft soil subgrade in the Haiou Island section of Nansha Bridge, a comprehensive geological survey and soil analysis were conducted. Based on the analysis results, a corresponding design scheme for the soft soil subgrade was formulated to ensure bridge safety and stability. Furthermore, various reinforcement measures such as compaction, drainage, and lightweight soil were implemented to mitigate the impact of soft soil filling on the bridge structure. To evaluate the effectiveness of our treatment method, post-construction effect testing was performed using both static pressure and vibration acceleration methods. The static pressure method provided crucial parameters related to bearing capacity and compressibility of the soft soil subgrade while vibration acceleration analysis reflected response characteristics under dynamic load conditions. By comparing and analyzing results obtained from these two methods comprehensively evaluated feasibility of our treatment approach. Finally, based on experimental study findings and data analysis outcomes, it is recommended that post-construction effect testing for Haiou Island section's soft soil subgrade should employ both static pressure method and vibration acceleration method along with targeted reinforcement measures selected specifically to minimize adverse impacts on bridge structure
Research on stress through photoelastic experiment and finite element method considering sliding wear
Get PDFSliding contact on the contact interface of friction pairs is a common type of contact. The sliding wear caused by sliding contact has an obvious influence on the stress in the contact area. In this study, the photoelastic experiment and finite element method are adopted to study variation laws of stress in the contact area. The results show that the stress in the contact region is very concentrated, and the contact half-width gradually ascends with the increase of sliding wear. The stress intensity in the contact region and von Mises stress at the contact centre decrease with the increase of wear depth. In the case of a wear depth of less than 0.3 mm, the stress intensity and the contact stress decrease rapidly with the growth of wear depth. When the wear depth exceeds 0.3 mm, the influence of wear depth on the stress intensity and contact stress is small. The results of this research clarify the effect of sliding wear on the stress in the contact area, and provide a reference for studying the contact issues
Low-level laser therapy parameters in the treatment of Orofacial pain in temporomandibular disorder
Get PDFTemporomandibular disorder (TMD) comprises a group of dysfunctions of the masticatory system involving joint, myofascial, and even sensory alterations. The main symptom of TMD is orofacial pain, which has a negative impact on the quality of life of TMD sufferers, affecting their productivity at work and school, the quality of their sleep, their appetite, and their satisfaction with life. An alternative for the treatment of TMD is the low-level laser therapy (LLLT), which stimulates cellular functions and promotes therapeutic effects. However, there is no consensus in the literature. Objective: This review aimed to elucidate the parameters of low-level laser therapy in the treatment of orofacial pain in patients with temporomandibular disorder. Methods: A search was carried out for scientific articles published between 2013 and 2023 in the MEDLINE, PEDro, LILACS and SciELO databases. Results: A total of 21 studies were previously selected and after the eligibility criteria, 10 studies were included. Can be suggest a protocol for treating patients with temporomandibular disorder by low-level laser therapy with the following parameters: infrared wavelength, energy density less than 10 J/cm2, output power from 100 to 250 mW and at least 8 sessions of treatment. Conclusion: The low-level laser therapy improves orofacial pain in patients with temporomandibular disorder
A bulk queue’s analysis with two-stage heterogeneous services, multiple vacations, closedown with server breakdown, and two types of renovation
Get PDFA queueing system with two stages of heterogeneous services, multiple vacations, and closedown upon server failure is considered in this study for MX/Ga,b data. Two different services must be provided to a group of customers one at a time. At time C, the server finishes its shut-down procedures following the conclusion of each SPS. A server that has a queue length shorter than a takes numerous, different-duration vacations. Upon returning from vacation, if the server detects that there are less than a customers in the queue, they will continue to serve the following batch if the server determines that there are at least a customers waiting for service. During the server’s first phase of operation, the service channels will momentarily fail with a probability of (π1) at any time, and during the server’s second phase of operation, the service channels will fail with a probability of (π2) at any time
Maintenance decision-making and its relevance in engineering asset management
Get PDFEngineering asset management (EAM) has received a lot of attention in the last few decades. Despite this, industries struggle to identify the best strategies for maintaining assets. The decision-making around selecting a relevant maintenance strategy generally considers factors like risk, performance and cost. Risk management is, usually, largely subjective and industries consequently make investments in a subjective manner, making the allocation of budget unstructured and arbitrary. Generally, industries focus only on either overt risks or basic performance of assets, thus creating uncertainties in the decision-making process. Recently, however, maintenance decision-making has evolved from a subjective assessment, chiefly dependent on expert opinions, to utilizing live-data-sensor technology. The attitude towards component failures and how to address them has changed drastically with the evolution of maintenance strategies. Additionally, the emergence and use of several tools and models have assisted the drafting and implementation of effective maintenance strategies. These advancements, however, have only considered discrete parameters while modelling, instead of using an integrated approach. One of the primary factors which can address this shortfall and make the decision-making process more robust is the economic element. To enable an effective decision-making process, it is imperative to consider quantifiable determinants and include economic parameters while drafting maintenance policies. This paper reviews maintenance decision-making strategies in EAM and also highlights its relevance through an economic lens