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Performance assessment of pantograph and overhead system based on a vertical coupling dynamics model of the railway system
No full textThe increase of train speed leads to a violent vibration of the pantograph and overhead system. To evaluate the interaction performance of the pantograph and overhead system, a whole railway dynamics model including the track, vehicle, pantograph, and overhead system is established. The overhead system is represented by the finite element approach using the analytical formulas of nonlinear cable and truss elements. The vehicle is modeled by a multi-rigid-body system with a pantograph installed on its roof. A beam element with elastic foundations is used to model the track, which possesses harmonic and random irregularities. An iterative algorithm is implemented to solve the nonlinear behavior of the coupling model. The nonlinearities in the deformation of overhead system, the contact of the pantograph and contact line, and the contact of the vehicle-track are properly considered. Several numerical simulations are implemented to systematically investigate the influence of the vehicle-track vibration on the dynamic behavior of pantograph and overhead system. The results indicate that the vehicle-track vibration induced by the rail irregularities with large amplitude or certain wavelength can significantly aggravate the interaction performance of pantograph and overhead system
Structure-property modeling scheme based on optimized microstructural information by two-point statistics and principal component analysis
No full textConstruction of the structure-property (SP) relationship is an important tenet during materials development. Optimizing microstructural information is a necessary and challenging task in understanding and improving this linkage. To solve the problem that the experimental microstructures with a small size usually fail to represent the entire sample structure, a data-driven scheme integrating two-point statistics, principal component analysis, and machine learning was developed to reasonably construct a representative volume element (RVE) set from the small microstructures and extract optimized structural information. Based on the elaborate quantitative metrics and method, this kind of RVE set was successfully constructed on an experimental microstructure dataset of ferrite heat-resistant steels. Moreover, to remove redundant information included in two-point statistics, the critical threshold of the tolerance factor related to the coherence length in microstructures was determined to be 0.005. An accurate SP linkage was finally established (mean absolute error < 6.28 MPa for yield strength). This scheme was further validated on two other simulated and experimental datasets, which proved that it can offer scientific nature, reliability, and universality compared to traditional strategies. This scheme has a bright application prospect in microstructure classification, property prediction, and alloy design
Motion planning and tracking control of unmanned underwater vehicles: technologies, challenges and prospects
No full textThe motion planning and tracking control techniques of unmanned underwater vehicles (UUV) are fundamentally significant for efficient and robust UUV navigation, which is crucial for underwater rescue, facility maintenance, marine resource exploration, aquatic recreation, etc. Studies on UUV motion planning and tracking control have been growing rapidly worldwide, which are usually sorted into the following topics: task assignment of the multi-UUV system, UUV path planning, and UUV trajectory tracking. This paper provides a comprehensive review of conventional and intelligent technologies for motion planning and tracking control of UUVs. Analysis of the benefits and drawbacks of these various methodologies in literature is presented. In addition, the challenges and prospects of UUV motion planning and tracking control are provided as possible developments for future research
Facial expression recognition using adapted residual based deep neural network
No full textEmotion on our face can determine our feelings, mental state and can directly impact our decisions. Humans are subjected to undergo an emotional change in relation to their living environment and or at a present circumstance. These emotions can be anger, disgust, fear, sadness, happiness, surprise or neutral. Due to the intricacy and nuance of facial expressions and their relationship to emotions, accurate facial expression identification remains a difficult undertaking. As a result, we provide an end-to-end system that uses residual blocks to identify emotions and improve accuracy in this research field. After receiving a facial image, the framework returns its emotional state. The accuracy obtained on the test set of FERGIT dataset (an extension of the FER2013 dataset with 49300 images) was 75%. This proves the efficiency of the model in classifying facial emotions as this database poses a bunch of challenges such as imbalanced data, intraclass variance, and occlusion. To ensure the performance of our model, we also tested it on the CK+ database and its output accuracy was 97% on the test set
Carbon footprints of the Indian AFOLU (Agriculture, Forestry, and Other Land Use) sector: a review
No full textStabilizing greenhouse gas (GHG) emissions from croplands as agricultural demand grows is a critical climate change mitigation strategy. Depending on management, the Agriculture, Forestry, and Other Land Use (AFOLU) sector can be both a source as well as a net sink for carbon. Currently, it contributes 25% of the global anthropogenic carbon emissions. Although India’s emissions from this sector are around 8% of the total national GHG emissions, it can contribute significantly to the country’s aspirations of reaching net-zero emissions by 2070. In this review, we explain the carbon footprints of the AFOLU sector in India, focusing on enteric fermentation, fertilizer and manure management, rice paddies, burning of crop residues, forest fires, shifting cultivation, and food wastage. Furthermore, using the standard autoregressive integrated moving average method, we project India’s AFOLU sector emission routes for 2070 under four scenarios: business as usual (BAU) and three emission reduction levels, viz., 10%, 20%, and 40% below BAU. The article focuses on how the AFOLU sector can be leveraged proactively to reach the net-zero emission goals. Increasing forest cover, agroforestry, and other tree-based land-use systems; improving soil health through soil management, better crop residue, and livestock feed management; emission avoidance from rice ecosystems; and reducing food waste are all important strategies for lowering India’s AFOLU sector carbon footprints
Carbon sequestration by forests and agroforests: a reality check for the United States
No full textClimate change is a major global threat affecting food security and sustainability. Land use systems involving trees have the potential to positively impact climate change by reducing atmospheric carbon dioxide (CO2) and providing long-term carbon (C) storage. This review evaluated the C sequestration potential of two major land use systems of the United States (US) involving trees, forests and agroforests, which can also provide other ecosystem services.The estimated total forest C stock on forest land in the US in 1990 was 50,913 Tg and another 1885 Tg remained in harvested wood and discarded wood products. From 1990 to 1995, total C stock rose by 2%, and from 2000 to 2005, it rose by 1.7%. The US forests collectively lose (flux) about 200 Mg C y-1 from disturbance and harvesting. Currently, about 12% of the conterminous US forest land is at high or very high risk of wildfire. Annually, insects and diseases could transfer ~ 21 Tg of live aboveground biomass to litter and woody debris pools. A scenario that targets an afforestation policy for rural landowners in the eastern US and a reforestation policy targeting understocked federal forest lands in the western would improve US annual sequestration compared to the baseline of 323 Tg CO2 eq yr-1 in 2015 to 469 Tg CO2 eq yr-1 in 2050.Agroforestry offers greater potential to increase C sequestration of predominantly agriculture-dominated landscapes than monocrop agriculture by storing C in above- and belowground biomass, soil, and living and dead organisms and further extending the duration of C in soils. The estimated total C sequestration of current alley cropping (211,938 ha), riparian buffers (640,732 ha), silvopasture (34 Mha), and windbreak (2.37 Mha) practices is 219 Tg C yr-1. The total C sequestration would be 240 Tg C yr-1 with 5% of the US cropland converted to alley cropping (3.7 Tg yr-1), 15-m wide riparian buffers on both sides of 5% of the total stream length (4.75 Tg yr-1), 34 Mha converted to silvopasture (207 Tg yr-1), and windbreaks on 5% (7.45 Mha) of the cropland (25 Tg yr-1). Despite many limitations including uncertainty of land areas under agroforestry, lack of standardized estimation protocols, and lack of accountability on various C stocks (source-sink services, detritus C, insect/pest damages, etc.), we believe these new accrual rates and the land areas under each practice are much more realistic as new information became available over the last decade.The total C sequestration by forests (776) and agroforests (219) is 995 Tg yr-1 and represents approximately 15% of the US CO2 emissions. This review highlights the importance of sustainable management of forests and integration of agroforestry on agricultural lands to mitigate climate challenges further while meeting society’s need for food and a healthy environment
Serum and tissue light-chains as disease biomarkers and targets for treatment in AL amyloidosis
No full textAmyloid light-chain (AL) amyloidosis is the most common type of systemic amyloidosis and is a multi-organ disease affecting mostly the heart and kidneys. AL amyloidosis is a protein misfolding disorder characterized by the tissue deposition of monoclonal light chains (LCs) produced by neoplastic plasma cells. Measurement of circulating free LC (FLC) is an important tool for diagnosis, risk stratification, and management of AL amyloidosis and can be performed through antibody-based methods or mass spectrometry. Furthermore, correct identification of LC deposits in tissues is essential to diagnose AL amyloidosis. Together with antibody-based techniques, methods relying on mass spectroscopy are now available
Association between genome-wide epigenetic and genetic alterations in breast cancer tissue and response to HER2-targeted therapies in HER2-positive breast cancer patients: new findings and a systematic review
No full textRecent evidence suggests that genetic and epigenetic mechanisms might be associated with acquired resistance to cancer therapies. The aim of this study was to assess the association of genome-wide genetic and epigenetic alterations with the response to anti-HER2 agents in HER2-positive breast cancer patients. PubMed was screened for articles published until March 2021 on observational studies investigating the association of genome-wide genetic and epigenetic alterations, measured in breast cancer tissues or blood, with the response to targeted treatment in HER2-positive breast cancer patients. Sixteen studies were included in the review along with ours, in which we compared the genome-wide DNA methylation pattern in breast tumor tissues of patients who acquired resistance to treatment (case group, n = 6) to that of patients who did not develop resistance (control group, n = 6). Among genes identified as differentially methylated between the breast cancer tissue of cases and controls, one of them, PRKACA, was also reported as differentially expressed in two studies included in the review. Although included studies were heterogeneous in terms of methodology and study population, our review suggests that genes of the PI3K pathway may play an important role in developing resistance to anti-HER2 agents in breast cancer patients. Genome-wide genetic and epigenetic alterations measured in breast cancer tissue or blood might be promising markers of resistance to anti-HER2 agents in HER2-positive breast cancer patients. Further studies are needed to confirm these data
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