Study of interference fit between steel and brass parts

Interference fits are generally used in mechanical systems because they have low-cost production and their assembly parts are much smaller than other mechanical joints. Also, their geometric shapes and material properties allow technicians to actively determine how strong the fits are. In this study, let’s present research on interference fits between steel and brass assembly parts. The experimental processes were accomplished with five pairs of specimens to evaluate the behaviours of surface asperities under a high loading condition. Specifically, the specimen pair includes a C45 steel shaft and a C2680 brass hub, which have different surface roughness values (Ra). Let’s apply high-precision methods in measuring all dimensional parameters and employed axial load tests for distinctively inspecting the steel-brass interference fit performance. In every experiment, the measured responses are: 1) the surface roughness values (Ra) before and after loading cycles; 2) the axial load (Fa); 3) the relative displacement value or the real-time interface length in loading stages (l). The aim of this study is to propose a new relative interference value specifically between steel and brass assembly parts, which can help determine the interference loss value more accurately. It was not concluded that with the relative interference of 2.25 ‰ the load capability of steel-brass interference fits is extended. Besides, let’s narrow down the predictive loss coefficient (a) for steel-brass interference assemblies ranging from 1.1 to 2.1, which varies from widely used standards considering a=3. This result helps minimize inaccuracies in interference fit designs, calculations, and work capabilities

HYDROGEN DEFECTS ON THE SURFACE OF LEAD-FREE FERROELECTRIC Na0.5_{0.5}Bi0.5_{0.5}TiO3_3 MATERIALS

Hydrogen atomic chemisorption and adsorption at all possible vacancy sites on the surface of perovskite Na0.5Bi0.5TiO3 (110) were explored using calculations from density functional theory. Our calculations reveal that a pristine Na0.5Bi0.5TiO3 (110) surface can exhibit direct and indirect transitions characterized by optical bandgaps of 2.68 eV and 2.75 eV, respectively. The density of states of the Na0.5Bi0.5TiO3 (110) surface indicates predominant electron transitions from O-2p valence bands to Ti-3d and Bi-6p conduction bands in the low-energy range. Hydrogen substitution at vacancies can induce magnetism, whereas hydrogen adsorption enhances both the magnetism and conductivity of the surface system. In particular, the charge density reveals electron transfer between cations and hydrogen atoms, providing insight into the variations in hydrogen bonding properties in these surface systems. These observations expand our understanding of hydrogen chemisorption and adsorption on defect sites, providing a novel avenue for investigating and potentially developing environmentally friendly multiferroic materials for advanced electronic devices

A Generalization Bound of Deep Neural Networks for Dependent Data

Existing generalization bounds for deep neural networks require data to be independent and identically distributed (iid). This assumption may not hold in real-life applications such as evolutionary biology, infectious disease epidemiology, and stock price prediction. This work establishes a generalization bound of feed-forward neural networks for non-stationary $\phi$-mixing data

Isolation and characterization of chlorpyrifos-degrading bacteria in tea-growing soils

The excess use of pesticides in the agricultural sector has caused environmental pollution and affected the complete ecosystem. Among the various commonly used pesticides, chlorpyrifos (CPF) is widely used against multiple agrarian pests due to its effectiveness and higher insecticidal activities. However, along with its beneficial usage, CPF has various residual effects on the environment, causing multiple negative impacts on aquatic organisms and human health. Consequently, methods for eliminating CPF in the background are essential. Among the currently available approaches to CPF remediation, biological methods using microorganisms are eco-friendly and cost-effective. Therefore, this study was conducted to isolate and characterize chlorpyrifos-degrading bacteria from the tea-growing soil of Vietnam. For this, soil samples were collected from the 20 tea-growing areas of Vietnam. From the collected samples, three bacterial strains viz., Methylobacterium populi CNN2, Ensifer adhaerens VNN3, and Acinetobacter pittii CNN4 have been isolated by using streak plate method and identified based on 16S rRNA gene analysis. The study results showed that under laboratory conditions, E. adhaerens VNN3 had the highest CPF degradation ability and was followed by the strain M. populi CNN2. In liquid medium, CPF concentration (100 mg/L) was reduced by 95.2% and 81.4% by E.adhaerens VNN3 and M. populi CNN2, respectively, after 72 h. Further, under in-vitro conditions, the concentration of CPF was reduced from 500 mg/kg to 112 ± 1.73 (77.6%) and 197 ± 2.08 mg/kg (60.6%) by E. adhaerens VNN3 and M. populi CNN2, respectively. Based on the obtained results, it can be concluded that E. adhaerens VNN3 and M. populi CNN2 can be used for CPF-contaminated agricultural soil remediation

Fuzzy gain scheduling control apply to an RC Hovercraft

The Fuzzy Gain Scheduling (FGS) methodology for tuning the Proportional – Integral – Derivative (PID) traditional controller parameters by scheduling controlled gains in different phases, is a simple and effective application both in industries and real-time complex models while assuring the high achievements over pass decades, is proposed in this article. The Fuzzy logic rules of the triangular membership functions are exploited on-line to verify the Gain Scheduling of the Proportional – Integral – Derivative controller gains in different stages because it can minimize the tracking control error and utilize the Integral of Time Absolute Error (ITAE) minima criterion of the controller design process. For that reason, the controller design could tune the system model in the whole operation time to display the efficiency in tracking error. It is then implemented in a novel Remote Controlled (RC) Hovercraft motion models to demonstrate better control performance in comparison with the PID conventional controller

Effect of Toposequence Position on Soil Properties and Crop Yield of Paddy Rice in Northern Mountainous Region, Vietnam

Symposium Pape

Spatial differences in soil properties, crop yield and methane emission from paddy rice cascade, Northwest Vietnam

Session 2: Nitrogen, Green House Gasses and Agricultur

Cost optimization of two-stage helical gearboxes with second stage double gear-sets

In practice, the cost of a gearbox plays a very important role in the trade. Therefore, reducing the cost of gearboxes is an important task not only when manufacturing the gearboxes but also when designing them. In order to reduce the cost of a gearbox, there are many solutions in which determining the optimal partial gear ratios of a gearbox is an effective measure. This is because it not only the size, the mass but also the cost of a gearbox depends greatly on the partial gear ratios. This work presents a method for calculating the cost function of two-stage helical gearboxes with second-stage double gear-sets based on the mass of the components that construct the gearbox. The cost objective function is minimized to achieve the optimal transmission ratios. Furthermore, screening experiments are carried out with nine important input parameters that have significant effects on the optimum transmission ratio of the second stage. These parameters are the total gearbox ratio, the coefficient of wheel face width of the first stage, coefficient of wheel face width of the second stage, the allowable contact stress of the first stage, the allowable contact stress of the second stage, the output torque, the cost of gearbox housing, the cost of gears, and the shaft cost. The experimental results of were analysed by using the Analysis of Variance (ANOVA) method with the help of Minitab 19 software. The results demonstrate that the effective weight of the input parameters and their interactions on the output response was investigated. Also, a regression model for computing the optimal transmission ratio of the second stage was proposed. This brings significance not only in the design process but also in manufacturing since the gearbox cost can decreas

A nitrogen-doped carbon-coated silicon carbide as a robust and highly efficient metal-free catalyst for sour gas desulfurization in the presence of aromatics as contaminants

A mesoporous N-doped carbon coating for SiC extrudates shows excellent H2S desulfurization performance along with remarkably high resistance towards deactivation/fouling in the presence of aromatics as contaminant