Month: April 2024

Abstract

Leakage currents accelerate surface degradation of metal contacts via small scale arcing across lubricating films, but recent observations suggest that metallic nanoparticle additives in lubricants may be useful to improve contact performance. These findings prompted a study that examined electrically induced surface pitting of steel contacts in the presence of several lubricating greases including some containing nanometer-sized colloidal silver (Ag) particles. Reciprocating rolling sphere-on-disk experiments were conducted under electro-tribological loads employing polyurea greases derived from mineral and synthetic base oils with and without additives. Friction forces and electrical resistance were monitored continuously during the tests; surface changes were characterized by means of optical spectroscopy, stylus profilometry, and scanning electron microscopy (SEM) including compositional analysis using energy dispersive spectroscopy (EDS). The observations demonstrate that surface pitting induced by arcing occurs mainly at the points were the rolling motion changes direction and that eroded metal is deposited along the wear grove. Micron-sized pits are formed which contain carbon and oxygen indicating that arcing causes decomposition of the hydrocarbon lubricants. Numerous findings indicate a significant inhibition of pitting is induced by the Ag nanoparticles; some greases containing other additives exhibit a similar, although less pronounced, effect.

Abstract

Online social networks (OSNs) have gained popularity as platforms for professional, personal, and social networking. However, they are also vulnerable to fraudulent events such as rumors or fake news, which can mislead users and have serious consequences. The dissemination of misinformation on social networking sites has become a global threat. To address this, a novel model GO-3DANB is proposed to utilize a three-stream, double attention network-modified BiLSTM (3S-A2 DenseNet-modified BiLSTM) with Gannet optimization algorithm (GOA) to predict Sybils in OSNs. The GO-3DANB model extracts network weights and crucial characteristics using the 3S-A2 DenseNet-modified BiLSTM to automatically extract higher and lower features from social network fake account (SNFA) input data. The SNFA dataset, containing 17 metadata features from fake and real profiles and a total of 921 data points, is collected from Kaggle. The modified BiLSTM is used to establish forward correlation with input sequences and learn dependencies with input sequences in backward sequence, thereby completely extracting context information among various channels. We utilize GOA optimization to assess each individual's fitness for identifying Sybil's attacks. Our proposed method is evaluated using various metrics, including precision, sensitivity, accuracy, specificity, F1-score value, and receiver operating characteristic curve (ROC). In comparison to existing methods, our proposed method, GO-3DANB, achieves 96% accuracy, 96.34% precision, 95.31% specificity, 96.5% sensitivity, 0.96 F1-score value, and 0.97 ROC. Thus, our proposed method demonstrates the potential to address the problem of Sybil detection in OSNs and provides a valuable contribution to the field of Sybil security.

Abstract

The mission of Advanced Ionospheric Probe (AIP) onboard FORMOSAT-5 (F5) satellite is to detect pre-earthquake ionospheric anomalies (PEIAs) and observe ionospheric space weather. F5/AIP plasma quantities in the nighttime of 22:30 LT (local time) and the total electron content (TEC) of the global ionosphere map (GIM) are used to study PEIAs of an M7.3 earthquake in the Iran–Iraq border area on 12 November 2017, as well as signatures of two magnetic storms on 7 and 21–22 November 2017. Statistical analyses of the median base and one sample test are employed to find the characteristics of temporal PEIAs in GIM TEC over the Iran–Iraq area. The anomalous increases of the GIM TEC and F5/AIP ion density over the epicenter area on 3–4 November (day 9–8 before the M7.3 earthquake) agree with the temporal PEIA characteristics that the significant TEC increase frequently appears on day 14–6 before 53 M ≥ 5.5 earthquakes in the area during 1999–2016. The spatial analyses together with odds studies show that the PEIAs frequently appear specifically over the epicenter day 9–8 before the M7.3 earthquake and day 10–9 before a M6.1 earthquake on 1 December, while proponent TEC increases occur at worldwide high latitudes on the two magnetic storm days. The F5/AIP ion velocity uncovers that the PEIAs of the two earthquakes are caused by associated eastward electric fields, and the two positive storm signatures are due to the prompt penetration electric fields.

Abstract

E-commerce platform financing is a new service pattern of supply chain finance. However, this pattern may bring some new issues when considering the problem of cash flow shortage and financing difficulties of small and medium-sized enterprises. When enterprises use this service, they worry about the leakage of preferential wholesale price when applying the full loan amount and providing the true transaction information. Based on the model consisting of a supplier, a retailer and a cross-border e-commerce platform, the authors design a price masking strategy to prevent the retailer’s preferential wholesale price information from leakage. The authors analyze the profit of the retailer and the platform before and after adopting the price masking strategy. The authors find that the price masking strategy always benefits the retailer. Besides, the optimal profit of the retailer and the platform are both affected by the loan interest rate. Moreover, there exists a range of loan interest rates that can benefit both the retailer and the platform if the price masking strategy is adopted. The research emphasizes that platform can expand the total business volume by allowing retailers to use price masking strategy. In other words, there will be more and more retailers attracted by the strategy, which benefits the long-term growth of cross-border e-commerce platform financing.

Abstract

The arteriovenous fistula (AVF) is commonly faced with stenosis at the juxta-anastomotic (JXA) region of the vein. Implantation of a flexible nitinol stent across the stenosed JXA has led to the retention of functioning AVFs leading to the resulting AVF geometry being distinctly altered, thereby affecting the haemodynamic environment within it. In this study, large eddy simulations of the flow field within a patient-specific AVF geometry before and after stent implantation were conducted to detail the change in flow features. Although the diseased AVF had much lower flow rates, adverse flow features, such as recirculation zones and swirling flow at the anastomosis, and jet flow at the stenosis site were present. Larger velocity fluctuations (leading to higher turbulent kinetic energy) stemming from these flow features were apparent in the diseased AVF compared to the stented AVF. The unsteadiness at the stenosis created large regions of wall shear stress (WSS) fluctuations downstream of the stenosis site that were not as apparent in the stented AVF geometry. The larger pressure drop across the diseased vein, compared to the stented vein, was primarily caused by the constriction at the stenosis, potentially causing the lower flow rate. Furthermore, the WSS fluctuations in the diseased AVF could lead to further disease progression downstream of the stenosis. The change in bulk flow unsteadiness, pressure drop, and WSS behaviour confirms that the haemodynamic environment of the diseased AVF has substantially improved following the flexible stent implantation.

Abstract

Background

The coronavirus (COVID-19) pandemic and associated public health restrictions created unprecedented challenges for parents and their young dependent children. While psycho-social impacts of natural disasters on families are well studied, a typography of parent specific concerns in the COVID-19 context was yet to be articulated.

Objective

Using a bioecological systems framework, we adopted a mixed-methods research design to examine parents’ core concerns about the impacts of the pandemic on themselves and their children, testing for differences in concern foci of mothers compared with fathers.

Method

Data were drawn from the Australian Temperament Project Generation 3 (ATPG3) study, a prospective study of children born to a 40-year population-based cohort. During enforced COVID-19 lockdown restrictions between May to September 2020, ATPG3 parents (n = 516) were surveyed about their own and their children’s functioning in the context of the pandemic. Subject of qualitative content analysis, parents (n = 192) experiencing wellbeing concerns offered additional free-text responses about the nature of stress impacting themselves and their child/ren.

Results

Parents reported far-reaching impacts for themselves and their children across multiple bioecological systems. Core concerns were for emotional rather than physical health, specifically, for parents this was represented by increased levels of anxiety and stress, and for children, these impacts were notable from a developmental perspective. Greater frequency of parenting related concern was expressed by mothers in comparison to fathers.

Conclusions

Findings demonstrate the complex and interrelated nature of multi-systemic and gendered stressors impacting parents during the pandemic, and importantly point to modifiable risk factors which may inform early risk detection efforts.

Abstract

Migration and the dependence of rural communities on forest resources for subsistence have profoundly altered the composition and spatial structure of the landscapes of the border municipality of Kasenga in the southeast of DR Congo. The spatio-temporal dynamics of anthropogenic effects on forest ecosystems were mapped and quantified in the municipality of Kasenga using Landsat image classification from 1989 to 2022, combined with landscape ecology metrics to analyze spatial patterns. Our results show that the landscape has undergone profound disturbances. The area of large patches of forest that used to dominate the landscape has been reduced by a factor of 4 from 1989 to 2022, thus indicating the anthropogenic impact on the fragmentation of forest ecosystems. If in 33 years (from 1989 to 2022) forest has lost more than a third of their coverage through the dissection, fragmentation and attrition of patches, agriculture, grassland and wetland, and built-up and bare land have recorded a progressive dynamic resulting from the creation and aggregation of patches. These anthropogenic transformations, coupled with a lack of land management planning, will compromise the future of forest ecosystems since the level of landscape disturbance has quintupled from 1.1 to 5.5 in 33 years. There is then an urgent need to develop an integrated and participatory land management strategy to preserve forest resources and guarantee their resilience.