Service Conditions Research Articles

Train axlebox bearing composite fault denoising method based on SVMD and dual threshold classification criteria

Abstract The increase in train operating speed and the alteration of the wheel-rail contact relationship, which have resulted in a deterioration of the service conditions of axlebox bearings, render the composite bearing failure characteristics susceptible to being obliterated by robust background noise. In order to effectively filter out redundant noise and accurately extract the fault characteristics, a dual-threshold signal denoising method is constructed based on successive variational mode decomposition (SVMD) and combining the Euclidean distance and kurtosis characteristic (Dual-EDK). The validity of the proposed method is effective by the composite fault data of axlebox bearings on the equal scale test bench. Firstly, the signal is adaptively decomposed into K components by SVMD, which are classified into three categories by Dual-EDK: effective IMF, noisy IMF and noise IMF. Then, the effective IMF is retained, while the noisy IMF is discarded. Wavelet soft threshold (WST) is employed to reduce the noisy IMF, reconstruct effective IMF and denoising noisy IMF, and envelope demodulation is used to achieve noise reduction. Finally, the composite fault signals at both normal operating speeds and critical speed of instability are collated and subjected to analysis by the test bench. This is done in order to ascertain the efficacy of the proposed method by comparing the results with those obtained through the traditional approach. The results of the analysis demonstrate that, in comparison to VMD, the SNR is enhanced by 27.6% and the
RMSE is diminished by 7.4% at normal operating speeds, the SNR is augmented by 26.2% and the RMSE is reduced by 9.6% at the unstable critical speed. These outcomes illustrate that the proposed method is capable of effectively extracting the denoising characteristic components of bearing faults, and that it has a pronounced impact.

Privately Provided Public Service and Local Financial Condition: The Cost of Externalized Service Accountability

ABSTRACTObjectiveThis study investigates how special districts affect the financial condition of general‐purpose governments, specifically focusing on the nontraditional budgetary indicators focusing on the financial and service liabilities of local governments.MethodsBased on the extant literature, the concept of financial condition of local government is operationalized through solvency and efficiency type measures as well as a construct of local finance to capture the dependent variable's sophisticated characteristics. Using a balanced MSA year dataset between 1972 and 2017, the estimations run several empirical models with panel‐corrected standard error.ResultsThe estimation results generally indicate that the proliferation of special districts undermines the financial condition of cities and counties. While special districts may contribute positively to the local economy, their privately provided public services indirectly create financial stress. This burden falls on general‐purpose governments, particularly when social issues arise from insufficient universal service provision for the less affluent populations additionally.ConclusionThe findings indicate that general‐purpose governments are compelled to adopt less efficient methods to deliver comparable services to underserved constituent groups without access to specialized services, emphasizing that the creation of special districts often incurs greater costs than anticipated.

The spectral analysis of the state parameters of technical systems in the regular and damaged states

It is noted that reaction of bearing elements of structures and engineering components to service loadings, impacts of physical fields and corrosive environments is initiation not only fields of stresses and strains, but also fields of damages. At the same time depending on conditions of a loading and environment various mechanisms of accumulation of damages and fracture which indicators are essential changes in spectra of a response of technical systems to different impacts are realized. The analysis of parameters of a state of such systems by registration of spectral characteristics of service processes allows to carry out estimations of levels of their damage in rather full degree. On the basis of results of research of service states of technical systems on spectral diagnostic parameters approaches to the analysis of amplitude-frequency characteristicses of their actual states both in the regular allowed states, and upon transition to dangerous states owing to accumulation in them of dangerous service damages are offered. At the same time criteria of transition of technical systems from regular in emergency and catastrophic states at accumulation of critical limits of damage are formulated. Examples of the dispersed initiation of microcracks in material of structures parts at a cyclic deformation with their propagation in the main fractures, and also examples of the analysis of dynamic states on vibration spectra of a response of simple and compound technical systems with the crack which arose in them and with existence of defects are given. At the same time the possibility of obtaining initial computation and experimental information on parameters of a stress-strain state and damage of installation with use of methods of the spectral analysis of a response of a compound structure to vibration impact as a result of initiation of damage of its separate parts is shown. Results of such spectral analysis can be used for diagnostics and monitoring of conditions of regular service of high-loaded installations of a technosphere and transition of their states to limit emergency and catastrophic in relation to objects of power engineerings, space-rocket and aircraft equipment.

Relationships Between Common Distresses in Flexible Pavements and Physical Properties of Construction Materials Using an Ordinal Logistic Regression Model

Analytical models to predict distresses and service conditions of road pavements can greatly contribute to the development of an effective pavement management system. These models allow the transportation agencies to monitor and track the deterioration of pavements and consequently determine the needed maintenance operations to preserve the performance of the network. In this research, the pavement distresses and service conditions of the Indus Highway N-55 located in Karak district, Pakistan were examined. Distresses were identified by visual observation, and then their severity and extent were measured individually by using a Vernier caliper and a measuring scale. For each distress type, the corresponding PCR was calculated. The compaction densities of the base and wearing courses were considered as input parameters to develop an ordinal logistic regression model for two dominant distresses, namely rutting and potholes. Rutting severity and extent were divided into three levels, while pothole severity was divided into four levels. Bulk and maximum specific gravity were found to have a significant impact on the models of both distresses. The model can be used to predict their development in terms of severity and extent. The proposed formulation provides valuable insights into monitoring and predicting pavement distresses by assessing the densities of road construction materials.

Features of physical training cadets-intelligencers in modern conditions

The article examines the peculiarities of the organization of the educational process for the physical training of intelligence cadets in a higher military educational institution under martial law, and how the modern conditions of training and service of intelligence cadets affect their physical readiness. Research methods: theoretical analysis and generalization of educational and methodological recommendations by research topic, documentary method, comparison method. It has been established that the educational process of physical training of intelligence cadets of the Military Academy under martial law has certain features that negatively affect the level of physical fitness of future officers. The results of the conducted research indicate the need to increase the level of physical fitness of intelligence cadets during their studies at the Military Academy under martial law conditions, which will ensure their physical readiness to perform combat and special tasks as assigned in future military and professional activities.

Essential characteristics of the formation of readiness of future officers to use combat knives in extreme conditions of service and combat activity

The article examines the essential characteristics of the formation of future officers' readiness to use "Bladed weapons" in extreme conditions of service and combat activity. The relevance of the study is due to the growing requirements for professional training of military personnel, capable of effectively acting in complex and dangerous situations. Research methods: abstraction, analysis and synthesis, hypothetical-deductive method, induction and deduction, historical method, classification and systematization, comparative (comparative) method, logical method, modeling, forecasting, generalization and concretization, formalization. In addition, during the theoretical study, personal experience in organizing the system of special physical training of military personnel. The research identified key components of readiness to use edged weapons, including psychophysical preparedness, tactical literacy, legal awareness, and moral and ethical stability. Existing approaches to the formation of these competencies in the military education system are analyzed. Particular attention is paid to the integration of theoretical knowledge and practical skills, which provides future officers with the opportunity to adequately assess the situation, make informed and balanced decisions, and act in accordance with legislative norms. The results of the study can be used to improve the educational and training process of future officers in special physical training (tactical and tactical-special training), in particular for the development of specialized training programs aimed at preparing for the performance of assigned tasks in extreme conditions of service and combat activity. Prospects for further research include determining the criteria, levels (components) of forming the readiness of future officers to use "Bladed weapons" in extreme conditions of service and combat activity.

Results of the Experimental verification of Organizational and Pedagogical conditions for the formation of readiness of Future Physical Training and Sports Instructors for Professional activity

The article examines the problem of forming military-applied skills of hand-to-hand combat (measures of physical impact, force) in future physical training and sports instructors in the vocational education system. Organizational and pedagogical conditions aimed at improving the educational process of training military personnel of the National Guard of Ukraine have been developed and theoretically substantiated. A training model has been proposed that integrates modern pedagogical technologies adapted to the extreme conditions of service and combat activities. Research methods: observation, questionnaires and surveys, testing, pedagogical experiment, timing, expert evaluation, psychodiagnostics methods, modeling, statistical analysis (calculation of averages, correlations and other statistical indicators). In the process of research and analytical work, an approbation of experimental organizational and pedagogical conditions was carried out, which involves the development of special training situations, the use of simulation modeling methods, as well as the formation of psychophysical readiness to perform assigned tasks in extreme conditions of service and combat activity. The results of the study indicate an increase in the effectiveness of training for representatives of the studied category, which is confirmed by an increase in the level of mastery of the techniques and tactics of service-applied hand-to-hand combat, stress resistance, coordination abilities, and the ability to act in difficult conditions. The results obtained confirm the feasibility of introducing experimental organizational and pedagogical conditions into the system of professional education of future physical training and sports instructors. Prospects for further research in the chosen direction of scientific exploration include the development of an experimental program for organizing independent work of future physical training and sports instructors in the vocational education system.

Accelerating the design and discovery of tribocorrosion-resistant metals by interfacing multiphysics modeling with machine learning and genetic algorithms

Lightweight aluminum alloy is one of the widely used structural materials for various industries due to its low density, high strength-to-weight ratio, good corrosion resistance, and excellent recyclability. However, complex service conditions often result in material degradation due to simultaneous mechanical and corrosion attacks on the metal surfaces, such as tribocorrosion. This phenomenon represents a complex multiphysics challenge, wherein the tribocorrosion-induced material loss emerges as a function of varied environmental, mechanical, and electrochemical descriptors, each entailing distinct yet interlinked physical processes. The pursuit of simultaneous optimization across multiple material properties to enhance the overall tribocorrosion resistance is hampered by the inherent trade-offs between wear and corrosion resistance. Addressing this complexity, our study develops a novel methodology fusing machine-learning (ML) and genetic algorithm (GA)-based optimization techniques to tailor aluminum-based alloys for enhanced tribocorrosion resistance. Leveraging an experimentally validated multiphysics finite element analysis (FEA) model, we have used six key material parameters to model the tribocorrosion performance of Al alloys over a large property space. The ML model employs an ensemble method of artificial neural networks (ANNs) to predict the tribocorroded surface profile and total material loss based on FEA simulation results, significantly reducing computational time compared to conventional FEA methods. Crucially, our high-throughput screening pinpoints corrosion current density and yield strength as two pivotal parameters influencing tribocorrosion behavior. Harnessing GA optimization alongside the ML model, we efficiently identify a suite of optimal material properties—encompassing both mechanical and electrochemical aspects—for aluminum alloys, resulting in superior tribocorrosion resistance. This selection is substantiated through validation against high-fidelity FEA simulation results. This data-driven framework holds promise for tailoring tribocorrosion-resistant materials beyond aluminum alloys, adaptable to a wide range of metals and service environments.

Land use and landscape pattern changes in the Fenhe River Basin, China

The composition and pattern of ecosystems play a crucial role in determining the overall condition and spatial variations of ecosystem services. In this study, we explored the Normalized Difference Vegetation Index (NDVI), six land use/land cover change (LULC) types, and their landscape patterns to reflect spatial-temporal dynamics from 2010 to 2020 in the upper and middle reaches of the Fenhe River Basin. The trend analysis of Mann-Kendall tests was used to assess the NDVI variation of each pixel over the past decade. Shannon’s Diversity Index (SHDI) was used to quantify the complexity of the landscape pattern of local LULC. Meanwhile, the spatial-temporal dynamic variations of vegetation NDVI and six LULC types were illustrated using geographic mapping methods. The results were presented as follows: (1) From 2010 to 2020, vegetation cover increased, with an annual NDVI increment of 0.003 (P < 0.001). Spatially, there was a significant increasing trend in NDVI, particularly in high-altitude mountainous areas where the vegetation cover mostly consisted of forests or grasslands. However, there was no significant change in vegetation cover in the low-lying urban agglomeration area. (2) During the period from 2010 to 2020, there was a significant decrease in the area of water bodies and wetlands, the rate of decrease slowed from 2015 to 2020. Specifically, the percentage of decrease from 2010 to 2015 increased by more than 14%. This proportion exceeded 30% when compared to the final governmental ecological management goal set during the 13th Five-Year Plan Period (2016–2020). (3) During the same period, the SHDI of LULC exhibited heterogeneous characteristics. In the high-altitude areas near the river basin boundary, SHDI values were below 1.0. Conversely, in the low-altitude plains and urban areas with frequent human activities, SHDI values exceeded 1.0, reaching above 1.5 in urban areas. This study provides a scientific reference for the construction and management of the ecological environment in the Fenhe River Basin, along with practice insights for ecological protection and high-quality development in the Yellow River Basin.

Investigation of the Structural Characteristics of the Gas Diffusion Layer Using Micro-X-Ray Computed Tomography

Due to its low stiffness, the gas diffusion layer (GDL) exhibits significant deformation under a compression service condition, thereby exerting a nonlinear and strong coupling influence on fuel cells’ performance. Therefore, it is of great practical significance to study the structural characteristics evolution of GDLs. The microstructure of the GDLs was obtained using micro-X-ray computed tomography in this study, and their structural properties were analyzed comprehensively and quantitatively. The morphology of GDLs exhibited significant variations across manufacturers due to disparities in the materials and manufacturing processes. The distribution of the pore equivalent diameter and sphericity in GDLs conformed to a normal distribution, with irregular shapes. The fiber length distribution in the unit followed a Gamma distribution, showing a random and uneven distribution in the XY plane. When compressed, the average fiber length was reduced, and a substantial increase in isolated pores was observed. However, the quantity of long fibers and connected and isolated pores decreased after acidification treatment.

Effect of the transmission system on adhesion control and characteristics of a locomotive under different straight rail surface conditions

As the speed of heavy-haul trains is increased and transportation efficiency is improved, wheel-rail adhesion control has become a critical factor for train safety. Under the scenario of straight track, a dynamic model of the heavy-haul train considering the locomotive transmission system is established. Then, a wheel-rail adhesion control model is developed to research wheel-rail adhesion control and characteristics under complex service conditions, such as friction coefficients and train speeds. The results indicate that the wheelset angular acceleration and the wheelset longitudinal creepage considering the transmission system are larger than without considering the transmission system. Train speeds and friction coefficients are key factors affecting the adhesion control effect and characteristics. Effective control of the wheelset slipping is achieved. In the single torque control process, the torque adjustment time considering the transmission system is longer, the control efficiency is smaller and the control effect is worse. The transmission system will reduce the effect of adhesion control. Thus, it is necessary to consider the effect of the transmission system in adhesion control research.

Sensor for a Solid-Liquid Tribological System.

Solid-liquid lubrication systems have been widely used to enhance tribological behaviors. Alongside offering exceptional lubrication and wear-resistance performance, the active control of the tribological behavior of lubrication systems in accordance with service conditions is equally critical. To achieve this goal, accurately monitoring the condition of the lubrication system is fundamental. This review article aims to provide a fundamental understanding of different sensors for monitoring the condition of lubricants, as well as the friction and wear properties. Specifically, the sensors suitable for engineering applications are detailed introduced. Through this review, we wish to provide researchers in mechanical engineering with a clear technical overview, which can guide the design of intelligent lubrication systems with suitable sensors.

Assessing Health Service Accessibility for Community-Based Rehabilitation (CBR) Trainees in Malaysia: Implications for Inclusive Healthcare

ABSTRACT This study aims to examine the accessibility of Community-Based Rehabilitation trainees to public health services in Malaysia. Quantitative data were collected from 290 parents and guardians across 14 CBR locations using multi-stage simple random sampling. Accessibility to health services and facilities was measured in terms of service availability, suitability, convenience, and adequacy. A four-level Likert scale was employed to assess the condition of the health services and facilities. A questionnaire was employed, and data were analyzed using SPSS. Findings revealed high satisfaction with health campaigns (79.0%), preventive services (74.8%), healthy food programs (74.5%), medical treatment (73.8%), equipment/assistive services (74.1%), and rehabilitation/therapy (67.2%). Results demonstrated significant correlations between trainees’ self-change and satisfaction with health services. Improved accessibility to health services was shown to positively impact trainees’ ability to perform daily activities, highlighting the importance of tailored, accessible health programs in supporting the development and independence of individuals with disabilities.

Investigation of hygrothermal behavior of a novel bio-based panel: Experiment and numerical simulation

Straw composites, owing to their low carbon footprint and favorable hygrothermal properties, are becoming a promising alternative insulation material for buildings in order to promote energy saving and occupants’ comfort. However, the heat and moisture characteristics of straw composites at the material scale and under steady-state condition are insufficient for a thorough assessment of their performance as a building component in actual service conditions. This study focused on the hygrothermal performance of a novel bio-based wall made with a rice straw–alginate composite material. The temperature and relative humidity profiles within the wall were monitored under various boundary conditions. The inverse analysis method was proposed to determine liquid water permeability. In in a dynamic test, compared with the model of coupled heat-and-moisture transfer (CHM), the transient heat transfer model predicted temperature profiles with higher errors and underestimated total heat flux by up to 30.6%. Also, under the dynamic condition, the CHM model with liquid water transport showed decreased mean absolute errors by 61%, 57% and 8% at depths of 28 mm, 36 mm and 64 mm, respectively, compared with those predicted by the CHM model without liquid water transport. Both vapor transport and liquid transport seemed to be essential when modeling thermal transfer and moisture transfer through the wall.

Life predicting of typical electromechanical products under service conditions

Life predicting of typical electromechanical products under service conditions

Production of Honeycomb-Patterned Hybrid Ti2AlN/TiNi Films and Examination of Mechanical, Tribological, Adhesion and Fatigue Properties

Honeycomb-patterned hybrid Ti2AlN/TiNi films were produced on M2 and Inconel 718 substrates using a magnetron sputtering system. These films were subjected to heat treatment at 750°C. In the XRD patterns of annealed films, crystalline formations corresponding to the Ti2AlN MAX phase (honeycomb edge) and super elastic TiNi (honeycomb inner) films were achieved. Mechanical properties were separately determined for each film area due to the honeycomb-patterned hybrid Ti2AlN/TiNi films having two different film areas. The film deposited on Inconel 718 exhibited the highest hardness values, with 10.2 GPa for the TiNi film and 25.4 GPa for the Ti2AlN film. Considering the results of wear tests performed both at room temperature and at high temperature, it was detected that the friction coefficients and wear rates of the films decreased by at least 50% at high temperatures. Upon examining the adhesion performance of the films, the critical load values for the films deposited on M2 and Inconel 718 were 21 N and 26 N, respectively. According to the multi-pass scratch test results, it was observed that the film deposited on M2 maintained its structural integrity under a load of 7N and exhibited better fatigue performance. This study proved that multi-coating components with different geometric architectures can be produced in a single layer. It also showed that such hybrid coatings exhibit good performance in machine components operating under various service conditions.

Age- and sex-specific incidence rates and future projections for hip fractures in Zimbabwe

IntroductionPopulation ageing in Africa is increasing healthcare demands. Hip fractures require multidisciplinary care and are considered an indicator condition for age-related health services. We aimed to estimate current hip fracture...

High-strength aluminum matrix composites with strong bonding interfaces via in-situ amorphous alumina and plainification strategy

Silicon carbide particle (SiCp) reinforced aluminum matrix composites have potential applications for components under severe service conditions. However, their performance is commonly limited by challenges such as insufficient interfacial bonding strength, agglomeration and brittle interfacial reaction products. In this paper, the ultra-fine grained aluminum and in-situ formed amorphous alumina were fabricated, and the as-formed powder metallurgy SiCp/Al composites achieved excellent properties, with a high yield strength of 471 MPa and an ultimate tensile strength of 505 MPa, respectively. We systematically investigated the structures of the amorphous alumina, which bonds the SiCp and matrix together, improving the interfacial bonding strength and simultaneously suppressing the interfacial reactions. Notably, the proposed fabrication method is suitable for economic production of large-scale components and applicable for aluminum matrix composites with other types of reinforcements.

Simulating the effect of elevated temperature on the compressive strength of steel fiber reinforced concrete (SFRC) using ANSYS workbench

The behavior of concrete structures at elevated temperatures is of significant importance in predicting the safety of structures in response to certain accidents or particular service conditions. The behavior of M50 Steel Fiber Reinforced Concrete (SFRC) at 28-days strength subjected to elevated temperatures was simulated using ANSYS 2020 R2 Workbench, and results validated with experimental results from a referenced Journal. M50 concrete at 28-days was modelled along with steel fibers from 0 to 4% by weight of cement. Models were made and subjected at room temperature, 100, 200, 300, 400 and 500°C from ANSYS Workbench Static Structural module. The concrete matrix was modelled as solid body, while the steel fiber reinforcement as line bodies, the new ANSYS reinforcement workflow that allows for simulating proper bond between concrete and rebar was utilized. Compressive strength results were determined as Average Von-misses stress and results validates that obtained from the referenced literature. This work has developed results with variations compared to the experimental work largely below 5% and has given important reasons to assert that results obtained from experimental works can be obtained with FE simulations and that laboratory works can be simulated with FE programs to cut down on cost and time associated with the former. In other words ANSYS Workbench program is a good validatory tool for similar experimental research.

Fractional Order Kelvin-Voigt Constitutive Model and Dynamic Damping Characteristics of Viscoelastic Materials

Viscoelastic damping materials are often under complex service conditions. To precisely characterize its dynamic damping properties, based on fractional calculus and viscoelastic theory, considering the periodic characteristics of viscoelastic materials, the distributed fractional order Kelvin-Voigt constitutive model (DFKV) was constructed. The model accuracy was validated by quasi-static experiments. The dynamic modulus expressions were derived, and the model parametric feature analysis was carried out. Dynamic Mechanical Analysis (DMA) and Separate Hopkinson Pressure Bar (SHPB) experiments were performed with silicone rubber as the subject. The results show that the silicone rubber has an obvious temperature and frequency dependence, and it has a strong strain rate correlation considering that the strain rate effect indexes that are under high strain is 29.331. At the same time, clearly the viscoelastic dynamic constitutive behavior has phased characteristics that are in line with the scientific assumption of the distribution order. The fitting accuracy of DFKV model is higher than the existing contrast models, which reflects DFKV model and favorably represents the dynamic mechanical properties of viscoelastic materials under wide temperature, frequency and strain rate. The model is highly accurate, has fewer parameters, and the physical meaning of its parameters is clearer. It can provide a theoretical reference for the research and design of viscoelastic damping materials.