bluuebunny/crossref_metadata_2025 huggingface dataset:
Eocene animal trace fossils in 1.7-billion-year-old metaquartzites
Authors: Bengtson Stefan , Rasmussen Birger , Zi Jian-Wei , Fletcher Ian R. , Gehling James G. , Runnegar Bruce
Published: September 2021

Significance

Strained 1.7-billion-year-old metasedimentary rocks in southwestern Australia contain traces of burrowing animals, structures only known from the last half billion years of Earth history. As metamorphic events had made the sediment too hard for burrowing by ∼1.2 billion years ago, it has been suggested that the burrows were made during the Paleoproterozoic by early animals with no other fossil record. We found, however, that the quartzite had been deeply weathered by about 50 Mya, allowing burrowing during an Eocene flooding. Subsequent rehardening of the sediment by silica precipitation restored the impenetrable quartzite with its metamorphic fabric. However, the burrows lack that fabric and contain detrital grains that are much younger than the matrix in which they occur.
False discovery rate control in genome-wide association studies with population structure
Authors: Sesia Matteo , Bates Stephen , Candès Emmanuel , Marchini Jonathan , Sabatti Chiara
Published: September 2021

Significance

Genome-wide association studies compare a phenotype to thousands of genetic variants, searching for associations of potential biological interest. Standard analyses rely on linear models of the phenotype given one variable at a time. However, their assumptions are difficult to verify and their univariate approaches make it hard to recognize interesting associations from spurious ones. Our work takes a different path: We analyze all variants simultaneously, modelling the randomness in the genotypes, which is better understood, instead of the phenotype. Our solution accounts for linkage disequilibrium and population structure, controls the false discovery rate, and leverages powerful machine-learning tools. Applications to the UK Biobank data indicate increased power compared to state-of-the-art alternatives and high replicability.
Bacteria hinder large-scale transport and enhance small-scale mixing in time-periodic flows
Authors: Ran Ranjiangshang , Brosseau Quentin , Blackwell Brendan C. , Qin Boyang , Winter Rebecca L. , Arratia Paulo E.
Published: September 2021

Significance

How does the swimming motion of bacteria affect the mixing of passive scalars in chaotic flows? Answers to this question can lead to a better understanding of the formation of algal blooms in oceans and lakes, as well as potentially useful applications in vaccine and biofuel production. Our experiments show that the presence of swimming
Escherichia coli
in two-dimensional chaotic flows can hinder large-scale transport and reduce flow chaoticity. Locally, however, bacteria can significantly enhance small-scale mixing. Our simulations also reveal the potential mechanism for these phenomena being the transient accumulation and dispersion of bacteria near regions of large fluid stretching.
China's low fertility may not hinder future prosperity
Authors: Marois Guillaume , Gietel-Basten Stuart , Lutz Wolfgang
Published: September 2021

Significance

China has the world’s largest national population and is rapidly catching up with the United States in terms of having the status as the world's largest economy. In this context, recent reports about unexpectedly low levels of fertility have given rise to speculation that the resulting population stagnation/decline and rapid aging may pose a major obstacle to continued prosperity in the future. We show that, depending on the indicator of demographic dependency used, the future may look very different. When associated with rapid increases in human capital, low fertility rates may not pose such a significant obstacle to continued development over the coming decades. Whether this will be the case may have profound geopolitical and global economic consequences.
Propagation of waves in high Brillouin zones: Chaotic branched flow and stable superwires
Authors: Daza Alvar , Heller Eric J. , Graf Anton M. , Räsänen Esa
Published: September 2021

Significance

Waves propagating through random media can accumulate in strong branches, intensifying fluctuations and powerful phenomena such as tsunamis. However, branched flow is not restricted to the large scale, and here, we find surprisingly that branched flow is not restricted to random media. We show that quantum waves living in the high Brillouin zones of periodic potentials also branch. Moreover, some of these branches do not decay as in random media but remain robust indefinitely, creating dynamically stable channels that we call superwires. The waves in these stable branches have enough energy to surmount the channel potential and go elsewhere, but classically, nonlinear dynamics keeps them confined within the channel. These results have direct experimental consequences for superlattices and optical systems.
Midbrain dopaminergic innervation of the hippocampus is sufficient to modulate formation of aversive memories
Authors: Tsetsenis Theodoros , Badyna Julia K. , Wilson Julianne A. , Zhang Xiaowen , Krizman Elizabeth N. , Subramaniyan Manivannan , Yang Kechun , Thomas Steven A. , Dani John A.
Published: September 2021

Significance

The origin and mode of action of dopamine on hippocampus-dependent memory have been a matter of interest for many years. The latest research has pointed toward the locus coeruleus as the main source of hippocampal dopamine, while inputs from midbrain dopaminergic centers remain controversial and understudied. We provide anatomical evidence for a direct dopaminergic projection to the hippocampus from a distinct, identified midbrain population and report a bidirectional modulation of hippocampal-aversive learning by midbrain dopamine. Our data indicate that this modulation is sustained even in the absence of catecholamine release from the locus coeruleus. These results demonstrate that midbrain dopaminergic innervation of the dorsal hippocampus is significant and plays a functional role in the modulation of aversive memory formation.
Technical aspects of cardiorespiratory estimation using subspace projections and cross entropy
Authors: Morales John , Moeyersons Jonathan , Testelmans Dries , Buyse Bertien , Borzée Pascal , Van Hoof Chris , Groenendaal Willemijn , Van Huffel Sabine , Varon Carolina
Published: September 2021

Background. Respiratory sinus arrhythmia (RSA) is a form of cardiorespiratory coupling. Its quantification has been suggested as a biomarker to diagnose different diseases. Two state-of-the-art methods, based on subspace projections and entropy, are used to estimate the RSA strength and are evaluated in this paper. Their computation requires the selection of a model order, and their performance is strongly related to the temporal and spectral characteristics of the cardiorespiratory signals. Objective. To evaluate the robustness of the RSA estimates to the selection of model order, delays, changes of phase and irregular heartbeats as well as to give recommendations for their interpretation on each case. Approach. Simulations were used to evaluate the model order selection when calculating the RSA estimates introduced before, as well as three different scenarios that can occur in signals acquired in non-controlled environments and/or from patient populations: the presence of irregular heartbeats; the occurrence of delays between heart rate variability (HRV) and respiratory signals; and the changes over time of the phase between HRV and respiratory signals. Main results. It was found that using a single model order for all the calculations suffices to characterize RSA correctly. In addition, the RSA estimation in signals containing more than 5 irregular heartbeats in a period of 5 min might be misleading. Regarding the delays between HRV and respiratory signals, both estimates are robust. For the last scenario, the two approaches tolerate phase changes up to 54°, as long as this lasts less than one fifth of the recording duration. Significance. Guidelines are given to compute the RSA estimates in non-controlled environments and patient populations.
Shape resonances and the T

c
dependence on film thickness of Ni/Bi systems
Authors: Doria Mauro M , Liu Liying , Xing Yutao , Merino I L C , Litterst F J , Baggio-Saitovitch E
Published: September 2021

We report on the experimentally observed variation of the superconducting critical temperature (T

c
) of Ni/Bi systems as a function of the total deposited film thickness and on its explanation using a theoretical model. Two series of Ni/Bi systems have been analyzed which were obtained by depositions of Ni onto Bi in the proportions Ni3Bix (3 nm of Ni onto x nm of Bi) and NiyBi6y (y nm Ni onto 6 y nm of Bi). As shown recently, the formation of the superconducting compound NiBi3 at Ni/Bi interfaces in the resulting NiBi3-Bi films is thermodynamically favored by a volume contraction. Here we corroborate this result and estimate the thickness of the resulting NiBi3 and of the remaining Bi layers for the Ni3Bix and NiyBi6y series using the laws of mass and conservation of number of atoms. We consider the resulting film as being made up of two homogeneous and uniform layers of NiBi3 and Bi, respectively, and study this idealizing model using the Bogoliubov de Gennes (BdG) equations. It is assumed that superconductivity originates in the NiBi3 layer and penetrates the Bi layers via a potential barrier. Our theoretical calculations predict the dependence of T

c
with respect to the thicknesses of the NiBi3 and Bi layers, and also with the strength of the potential barrier that blocks the migration of electrons from the NiBi3 to the Bi layer. The calculations show that the superconducting gap also exists in Bi, although much weaker than in the NiBi3 layer. We compare the predicted T

c
values with the experimental data and find sufficient agreement to suggest that our model can explain the experimentally observed variation of T

c
with thickness. We interpret this dependence as shape resonance oscillations which are derived from the BdG theory applied to thin superconducting films.
Markovian dynamics in de Sitter
Authors: Mirbabayi Mehrdad
Published: September 2021

The equilibrium state of fields in the causal wedge of a dS observer is thermal, though realistic observers have only partial access to the state. To them, out-of-equilibrium states of a light scalar field appear to thermalize in a Markovian fashion. We show this by formulating a systematic expansion for tracing out the environment. As an example, we calculate the O(λ) correction to the result of Starobinsky and Yokoyama for the relaxation exponents of λϕ4 theory.
Latest results of Eurofusion plasma-facing components research in the areas of power loading, material erosion and fuel retention
Authors: Reinhart M. , Brezinsek S. , Kirschner A. , Coenen J.W. , Schwarz-Selinger T. , Schmid K. , Hakola A. , van der Meiden H. , Dejarnac R. , Tsitrone E. , Doerner R. , Baldwin M. , Nishijima D. , Team WP PFC
Published: September 2021

The interaction between the edge-plasma in a fusion reactor and the surrounding first-wall components is one of the main issues for the realisation of fusion energy power plants. The EUROfusion Work Package on plasma-facing components addresses the key areas of plasma-surface interaction in view of ITER and DEMO operation, which are mostly related to material erosion, surface damage and fuel retention. These aspects are both investigated experimentally (in tokamaks, linear plasma devices and lab experiments) and by modelling. Here, selective results regarding the main research topics are presented: in the area of tungsten (W) surface modifications, the interplay between W fuzz formation and W fuzz erosion depends strongly on the local plasma and surface conditions, as demonstrated by tokamak experiments. Complementary, experimental findings on the dependence of erosion on the surface structure in lab-scale experiments have led to the successful implementation of surface structure effects in numerical modelling. The qualification of ITER-like monoblocks at high fluences of up to 1031 D m−2 in linear plasma facilities has shown no visible damages at cold plasma conditions. However, experiments with simultaneous plasma and pulsed heat loading (edge-localized modes simulations) show that synergistic effects can lower the W damage thresholds. Additionally, fuel retention studies show that nitrogen as a plasma impurity increases the fuel retention in W, and that deuterium implanted in the surface of W is capable of stabilizing displacement damages caused by neutron damage. Finally, the implications of these results on ITER and DEMO operation are discussed and an outlook on follow-up experiments is given: the results indicate that there are possible impacts on the ITER divertor lifetime and tritium removal. Other areas like the divertor shaping and the erosion need additional investigations in the future to quantify the impact on ITER and DEMO operation.
The substitution of Mg2+with Mn2+/4+metal ions in chlorophyll structure isolated from Gliricidia sepium leaves
Authors: Selan O T E , Hawu H N , Poy L , Cunha T D , Darmakusuma D
Published: September 2021

One of the critical issues of using chlorophyll (Mg-Chl) as a dye photosensitizer in DSSC is related to a rapid decay of this material. Changing the alkali metal using transition metal ions could theoretically increase the stability of chlorophyll. In this research, the substitution of Mg2+with Mnn+ions (n = 2 and 4) in chlorophyll structure isolated fromGliricidia sepiumleaves had been carried out. The column chromatography technique was chosen to separate the chlorophyll followed by modifying the metal centre using two different compounds containing manganese, namely MnCl2and MnO2. The results show that there are differences in Rf values after substitutions, [0.90 (Mg-Chl), 0.81 (Mn2+-Chl), and 0.96 (Mn4+-Chl)]. The Soret bands experience a redshift from 330 to 338 nm for Mn2+-Chl and a blue shift from 411 to 401 nm for Mn4+-Chl while the Q band has a redshift from 665 to 668 nm for Mn2+-Chl but a blue shift from 665 to 526 nm for Mn4+-Chl. The obtained products have similar IR absorption patterns to Mg-Chl but differ only in its transmittance with slightly higher wavenumbers shifts. Shifting of UV-Visible and Infra-red characteristics indicate different molecular electronic nature of the obtained compounds. This implies successful substitution for the metal centre without damaging the structure of the chlorophyll.
Travelling salesman problem: Greedy single point crossover in ordinal representation
Authors: Fernandez B , Fanggidae A , Pandie E S Y , Mauko A Y
Published: September 2021

Genetic Algorithm (GA) is a metaheuristic algorithm which has stages; coding, selection, crossover, and mutation. The crossover operator plays an important role in producing offspring to find solutions. Single Point Crossover (SPC) and Two Point Crossover (TPC) are classic crossover operators that are easy to apply to ordinal representation coding rather than path representation coding. The greedy algorithm is applied to the SPC operator to solve the Traveling Salesman Problem (TSP) to improve the performance of the genetic algorithm in the ordinal representation coding scheme. The results show that the proposed Greedy Single Point Crossover (GSPC) has higher performance in finding the global optimal solution for all population sizes and cities used, but it costs computation time.
The mapping of potential ground water using geoelectrical measurement of Schlumberger configuration method in Malata Village, Tana Righu Sub-District, West Sumba District, East Nusa Tenggara Province
Authors: Krisnasiwi I F
Published: September 2021

This study aims to analyze rock units containing aquifers in the location of investigation using geoelectrical measurements with Schlumberger configuration method of the MC OHM 2115 Resistivity Meter. The estimation was carried out in 12 measurement points with the length of each path was 150 m. The data analysis of the measurement was implemented using IP2WIN software and Corel Draw X6 software. The results of the interpretation of the 12 measurement points indicated that there were 5 rock units, namely the resistivity 0 ≤ 2 Ohm m which is interpreted as clay. Resistivity 2, 5 ≤ 10 Ohm m as marl. Species resistivity 10.5 ≤ 20 Ohm m as marl limestone, while resistivity ≥ 20.5 Ohm m as reef limestone. The aquifer belongs in the reef limestone unit with a specific resistance of 20.5 ≤ 100 Ohm m which ends with an impermeable layer such as clay or semi impermeable such as marl. Based on the interpretation, it is concluded that along the measurement area there are aquifers with varying depths which can be optimized by means of drilling at points 01, 03, 04, 06, and 09. The location that has the thickest aquifer is point 04 (± 29.3 m) and 09 (± 38 m).
Automatic Localization of Condylar Process Centre Based on Generalized Hough Transform from CBCT images
Authors: Wang Tingkang , Zhang Songze , Shi Hongjian
Published: September 2021

Cone Beam Computed Tomography (CBCT) is a technique for capturing maxillofacial images that provide tissue views with low radiation doses. In this paper, we propose an automatic method to locate the centre of the mandibular condylar process in CBCT images. The bone edges of the condylar process are extracted to detect the mandibular ramus in each slice based on the generalized Hough Transform. We propose an upward region-growing method to segment the condylar and coracoid processes. The centre of the condylar process is then determined as the centre of the condylar region in the axial slice with the maximum condyle area. The centre located by the proposed method was compared with the centre manually located by two experts. Our results indicate that the proposed method can accurately locate the condylar process centre.
Shuffling-SinGAN: Improvement on Generative Model from a Single Image
Authors: Zheng Ming , Zhang Pengyuan , Gao Yining , Zou Hang
Published: September 2021

Recently, SinGAN takes the use of GANs into a new realm – unconditional generation learned from a single natural image. Following the SinGAN architecture, we propose Shuffling- SinGAN, an efficient unconditional generative model that trained on a single natural image for general image manipulation. Our new network includes a pyramid of fully convolutional GANs, in which each layer is responsible for learning the patch distribution at a different scale of the image. We can generate new samples with variability through our network, which have the function of maintaining the texture and global structure of the original image. New random image generated by the model after multiple training is different from the original image in detail. Inspired by sinIR, we decided to add random pixel shuffling to the network. After experimentation, we found that the changed model generated more random new samples. Shuffling-SinGAN allows generating new samples of arbitrary size and aspect ratio, that have significant variability, yet maintain both the global structure and the fine textures of the training image. User tests confirm that the generated samples are commonly confused to be real images. With quantitative evaluation, we show that Shuffling-SinGAN has competitive performance on random image generation.
Face feature matching based on semantic Information
Authors: Guo Jianlan , Chen Yuqiang , Li Jiaming , Xie Jiabao
Published: September 2021

Face feature matching problems have always been a very important research topic in the field of image processing. Face feature matching is always the most important part of common face recognition algorithms, but how to match features quickly and accurately is a quite essential and urgent problem to be solved. Therefore, we propose a face feature matching method which can effectively improve the matching efficiency and accuracy. For each feature point in the input image, face feature matching based on nearest neighbor ratio method requires global search for the best matching in the reference image. However, we find that such matching method can achieve better matching results, but it costs a lot of computing resources and time. Therefore, we use the feature vectors constructed by CNN convolution feature map to provide the local matching region based on semantic information for handcrafted descriptors after feature matching. Although two feature matching processes are used in this paper, the matching efficiency is improved several times compared with the traditional global search scheme. Experiments show that our proposed can be used as an important module of face recognition system to improve the accuracy of face recognition.
Correction of refractive and scattered image distortions in optical coherence tomography based on scalpel
Authors: Tang Ning , Fan Jinyu , Zhang Yunping , Shi Guohua
Published: September 2021

We describe a distortion correction algorithm for OCT images based on the scalpel. In this algorithm, the distorted OCT images are segmented into three parts depending on the seven customized fiducials. Image translation and image stitching are used to eliminate the majority of the distortions. After performing experiments with porcine eyes, we basically correct the optical distortions caused by the reflection and interlayer scattering effects. The correction error is less than 2%. Our algorithm could bring many potential applications in ophthalmic procedures.
Reliable Single-image Denoising for Adaptive Optics Scanning Laser Ophthalmoscopy
Authors: Chen Yiwei , He Yi , Wang Jing , Li Wanyue , Xing Lina , Gao Feng , Shi Guohua
Published: September 2021

A reliable single-image denoising method is presented for adaptive optics scanning laser ophthalmoscopy. This method firstly averaged multiple images and then used the averaged image as the reference to adjust the parameters of the filtering process that was subsequently applied to other individual images. Six filtering methods, including the mean, median, Gaussian, fast adaptive nonlocal synthetic aperture radar despeckling, K-single value decomposition, and block matching and three-dimensional filtering, were utilized. The effectiveness of our method was verified based on the comparison of sets of images without and with parameter adjustments. Furthermore, we applied the same parameter settings as those obtained from the filter adjustments of another adaptive optics scanning laser ophthalmoscope image acquired by the same instrument. The filtered images showed that the parameter-adjusted filters work well on other images, which is helpful for improving the image quality of adaptive optics scanning laser ophthalmoscope images.
Malware detection based on TF-(IDF&ICF) method
Authors: Qin Bin , Zhang Junpeng , Chen Hongyu
Published: September 2021

As the level of information technology continues to increase, information security problems caused by malware are becoming more and more serious. An important method to detect malware is to analyze software behavior information, such as permissions, API call sequences and system calls. In this paper, API call sequences are used as the research object for malware detection, and the traditional feature extraction methods are not ideal for API call sequences. In this paper, a TF-(IDF&ICF) feature extraction method is proposed by mathematical analysis, which combines document and category level features. Experiments show that using the feature extractor proposed in this paper, followed by training, the performance is improved in four different machine learning models, and the F1 can reach 0.979, while the system response time is significantly reduced, which has good practical value.
Visual gesture recognition based on hand key points
Authors: Chen Boxu , Yu Lixin , Meng Xiao , Hua Yang
Published: September 2021

In recent years, computers have become a part of people's daily life, and the interaction between people and computers has increasingly become a hot spot in the field of scientific research. Gesture recognition based on vision is an indispensable part of the new generation of human-computer interaction. This paper presents a visual gesture recognition method based on hand key points, which realizes the detection of hand key points in the current input image and the recognition of defined gestures. It provides a new technical scheme for human-computer interaction application. Compared with the current mainstream solutions that directly train the defined gestures and obtain the gestures in the input image through template comparison detection, this paper first uses the rigid characteristics of the palm to design a palm detection model instead of directly detecting the entire hand. After detecting the presence of hand in the picture, the hand key point model locates 21 3D hand key point coordinates in the previously detected hand area through direct coordinate prediction. Finally, the meaning of gestures in the input image is obtained through the positional relationship between the key nodes. This solution achieves 95.7% of the accuracy of detection, and improves the FPS from 21-23 to 30-31.
Target-oriented Opinion Words Extraction via graph convolutional network
Authors: Li BaoKai , Dai YueMing
Published: September 2021

Target-oriented opinion word extraction (TOWE) is a sequence labelling subtask of aspect-level sentiment analysis (ABSA), which aims to extract corresponding opinion words for a given sentence and opinion target. In view of the existing related work, the structural information of sentences is not fully considered. In this study, we explore the integration of neural network and dependency tree to handle the TOWE and propose a model based on graph convolution network (GCN). The model uses the long short-term memory network (LSTM) to learn the semantic features of sentences. On this basis, the model uses the GCN to model the sentence structure through dependency tree and capture the syntactic dependency relationship between the target word and the opinion word. The experimental results show that GCN can effectively improve the performance of TOWE. The F1 values of the model on the semeval-rest14 and semeval-laptop14 reached 82.60% and 74.45%.
Research on Building Chinese Blog Semantic Lexicon Based on Semantic Comprehension
Authors: Wen Bin , Dong Huihui , Ding Ling , Dai Wenhua
Published: September 2021

Nowadays, investigators of phrases and text sentimental orientation identification mainly divided into two ways: semantic comprehension and machine learning. Machine learning needs a lot of training corpus and also cannot handle general field words effectively, meanwhile, semantic comprehension cannot get high scores at precision and recall. Therefore, in this paper, we propose a new fusion method based on our semantic comprehension for judging phrases’ polarity. In this paper, firstly, we modify the knowledge of Hownet, on the basis of its four primitives, the fifth primitive—sentimental primitive was proposed by our research, and annotated it into Hownet manually; secondly, we propose a new phrase sentimental similarity calculation method to compute word’s sentimental value; at last, we integrate transductive learning into this method to identify phrases’ sentimental orientation. The performance of experiment show that, compared with SVM or traditional semantic comprehension, it can get better results.
Short-Form video classification based on Gate shift module and Semantic embedding
Authors: Tao Jun , Han Lixin , Zhu Jun
Published: September 2021

Most of the existing video classification methods are based on large-scale data training, which can better realize the recognition and classification of known categories. However, data labelling is cumbersome and most things are unknown. Therefore, the existing video classification methods fall into a data bottleneck. This paper proposes a short video classification method based on GSM and semantic embedding. It uses super large-scale text information to assist the recognition process of the video classification model. This is an important development in the classification effect of knowledge categories. Specifically, this article expands the video classification method, adds category semantic embedding in the video feature extraction process, and trains to continuously fit the word vector of the corresponding category, and then uses semantic similarity to realize the classification of unknown categories. Multi-angle comparative experiments verify the effectiveness of this model, which can achieve good classification of unknown video categories.
A Review on Welding and Fatigue Behaviour of Titanium and Its Alloys
Authors: Kannan G.K. , Ramesh P. , Dhinakaran V. , Anandhraj R.
Published: September 2021

Titanium is metal element which comprises about 0.44% of earth’s crust. The abundance and reliable properties of this element made it essential in field of engineering works. Welding is a fabrication process which fuse the materials together. Welding of titanium and its alloys expands the applications of usage of titanium. The idea of this review, is to sum up the welding and fatigue behavior of titanium and its alloys. It has been identified that laser beam welding (LBW) is feasible for titanium and its alloys due to its flexibility, high heat capacity input and efficiency.
Micro-mechanics Study of Nano TiO2 High Friction Composite Material Using Pin on Disc Method
Authors: Kannan G K , Bernard S.Stephen , Ranjith L. , Jagadeep M.V. , Ganesh S.Jawahar , Santhosh S.Jawahar
Published: September 2021

This paper focuses with the analysis of friction and abrasion characteristics of Nano TiO2 composite using pin on disc method. Nano TiO2 with 10 ingredients was fabricated by employing compression moulding technique and also the composite tribology strength was weighd. The six composite specimens were prepared by varying Nano TiO2 (2, 4, 6, 8 and 10%) with other ingredients and the results are plotted. It indicates that the abrasion rate was decreased by adding Nano TiO2 upto 8%. Hardness and porosity are also found to increase but heat swell and specific gravity decreases. 6 wt% Nano TiO2 has the property to improve the friction stability during high speed and load. Abrasion tested composites was examined by scanning electron microscope indicating that abrasive, cavity and oxidation were the predominant abrasion mechanism. [Copyright information to be updated in production process]
Tensile and impact strength of alpaca fiber epoxy matrix hybrid composites prepared by injection moulding process
Authors: Vinoth N. , Rajkumar K. , Santhosh Kumar R. , Mohanavel V , Ravichandran M. , Sathish T. , Subbiah Ram
Published: September 2021

Today, there are many more applications for fibre reinforced polymer composites than there were for metals and alloys a few decades ago. Numerous research projects have focused on improving the mechanical and thermal properties of composite materials, especially when reinforced with environmentally friendly, recyclable, and biodegradable materials. This study combined alpaca fibre (AF), palm seed filler (PSF), and polypropylene (PP) to create composites that have improved properties over traditional polymer composites. Fiber loadings of 35, 30, 25, 20, 15, and 10 percent and filler loadings of 15, 10, and 5 percent were used to prepare the alpaca fiber/palm seed filler polypropylene (PP) composites using a conventional injection moulding technique (0, 5, 10, 15, 20 and 25 wt. percent ). Hydrophilicity and mechanical properties of the hybrid bio-composites were evaluated experimentally. The results showed that 15 lbs. For example, epoxy matrix composites have tensile and flexural strengths of 62 MPa, as well as hardness and impact strengths of 54 and 17.9 kJ/m2, respectively.
Strength of 3D prints with variable print orientation
Authors: Kishore R , Sivaraj S. , Dhinakaran V , Padma Pravin Prabhagar V.S , Jawhar Srinivas S
Published: September 2021

The purpose of this paper is to present the analysis of the efficiency and strength of 3D printed parts due to the variation shown in print orientation. Fused deposition modeling (FDM) is a widely used technique in which the melt extrusion method is used to deploy the thermal plastics as filaments in a specific pattern. In recent years, the revolutionary method has changed the field of rapid manufacturing. This has become one of the most common methods for printing polymer-based composite components. The investigation is done based on the print orientation effects on the macrostructure, the mechanical properties, and the strain field behavior of PLA (polylactic acid) filament. Based on the analysis, the properties of an object are optimized to increase mechanical strength when manufactured. By fixing the similar print properties across all different orientations helps to identify the differences in the structural and other mechanical properties, which projects a clear understanding of the impact received and thus provides a way to enhance the structural strength of the prints.
Topology optimization of an ATV wheel hub
Authors: Karthikeyan K , Kishore R , Jeeva K , Kumar Harin , Kannan R.S
Published: September 2021

The article is based on the Topology Optimization of an ATV Wheel Hub. So, we use this methodology to reduce the unwanted material of the All-Terrain Vehicle(ATV) Wheel HUB and to reduce the weight. ATV is mainly designed for a competition, where the Hub is used to connect the wheel to chassis via steering knuckles and arm linkages. Hub plays a vital role in the ATV. So, designing of hub should be in proper dimensions. The hub material is designed with a help of SOLIDWORKS. And it was analysed by SolidWorks simulation. The material used for a hub is Aluminium alloy 6063-T6.
Design of Buck Converter and PV Module for Solar Powered Sailing Boat
Authors: Ettappan M , Maheswaran G , Vimala V , Somasundaram K , Vishnupriyan J
Published: September 2021

The main intention of this work is to minimize the operating cost and increase the power generation of solar photovoltaic (PV) power-driven sailing boat with buck converter. The design of dc-dc converter for solar powered sailing boat is presented here. The entire PV source output power is taken and given to the solar boat through buck converter. The entire output power from the PV source which is given to the dc load is enough to drive a boat. The Buck converter model and solar PV module has been designed and simulated with the use of Matlab Simulink and compared with theoretical predictions.
Numerical simulation of the temperature distribution of elliptical cavity tube receivers in the parabolic trough solar collector
Authors: Cao Fei , Gu Xianzhe , Qiu Jialing , Yang Chunyuan , Zhu Tianyu
Published: September 2021

The elliptic cavity tube absorber is used in the parabolic trough solar collectors to increase the optical efficiency and decrease the thermal loss. But the non-uniform heat flux distribution on the tube receiver will cause non-uniform temperature distribution, thus leading to asymmetric thermal stress and deformation of the tube receiver. In this paper, the geometric as well as thermal parameters of the elliptical cavity tube receiver are analysed through numerical simulation. The temperature distribution of the tube receiver in the single-phase liquid zone, viz. the water zone and the vapour zone, is analysed. It is found from this study that there are two extreme temperature areas in the elliptical cavity tube receiver. When the major semi-axis of the elliptical cavity is 63mm, the maximum temperature of the water zone is the largest, which occurs at (-35mm, 0mm) of the tube receiver. When the major semi-axis of the elliptical cavity is 67mm, the maximum temperature appears at (-9mm, 0mm) in the vapour zone, and the minimum temperature rise appears at (-13.88mm, 0mm).
MOF derived carbon with ultra-high specific surface area and pore volume for lithium-ion capacitor cathodes
Authors: Yang Jian , Li Teng , Kashif Khan , Li Junxiang , Wu Mengqiang
Published: September 2021

Traditional supercapacitors have been studied extensively because of their high-power characters. However, their poor energy density severely limits its future applications. Different from the traditional supercapacitors, lithium-ion capacitors combine the high-power density of double-layer capacitors with the high energy density of lithium-ion batteries. In order to obtain the lithium-ion capacitors with such high performance, new electrode materials are inevitable. Herein, we use the metal-organic framework (MOF) technique to synthesize nano-sheets carbon-based materials with a large specific surface area and large pore volume. This new carbon-based material shows a very high specific capacity and long cycle life when being utilized in the cathode of lithium-ion capacitor. This method introduces a novel approach to the synthesis of high-specific surface activated carbon for lithium-ion capacitors.
Porous SiC Ceramics with Controllable Porosity Achieved by Micro-sized Powder through Recrystallization Sintering
Authors: Chen S , Chen C L , Huang Z L , Huang J S
Published: September 2021

Porous silicon carbide (SiC) ceramics with various porosity and pore size were successfully fabricated by adjusting the particle size and content of fine powder via recrystallization sintering process. The effects of the addition of fine powder with different particle size on the micromorphology of porous SiC ceramic and the flexural strength were investigated. With the increase of the fine powder content from 5wt% to 20 wt%, the porosity and pore size decrease, and the crystal grains gradually become larger and tend to round. The neck area among grains increases, leading to the improvement of flexural strength. The mechanism for promoting the sintering of porous SiC ceramics lies in the evaporation-condensation process of fine powder at high temperature. The finer particles are easier to be evaporated to promote the growth of coarse grain and the development of grain neck, so that the porosity and pore size were smaller, and the flexural strength was enhanced. At the addition of F4 powder of 20 wt%, the porous SiC ceramics with the porosity and MFP size of 39.1% and 1.38 μm respectively, and the flexural strength of 54.49MPa were obtained.
Ni-doped δ-MnO2 as a cathode for Zn-ion batteries
Authors: Gao Danmei , Zhu Tingting , Yu Li , Chen Peng , Li Chengjun , Liu Yuping
Published: September 2021

Among the cathode materials for zinc-ion batteries, manganese oxides have been extensively studied. Thermal decomposition method was adopted to synthesize the Ni-doped δ-MnO2 material, called as NixMn1-xO2. The electrochemical performance and energy storage mechanism of NixMn1-xO2 were studied in 2M ZnSO4 + 0.2M MnSO4 electrolyte. Nickel doping can significantly improve the electrochemical activity of δ-MnO2. Therefore, Ni-doped δ-MnO2 shows better electrochemical cycling performance than δ-MnO2. At 100 mA g−1, NixMn1-xO2 (x=0.2) the specific capacity of 280mAh g−1 in the second circle, and the corresponding voltage platform is 1.36V and 1.23 two discharge voltage platforms. After 100 cycles, the specific capacity of NixMn1-xO2 (x=0.2) still maintain 167 mAh g−1 at a current density of 100 mA g−1. In addition, we also proved that Zn2+ and H+ are co-intercalated into NixMn1-xO2 during the process of charge and discharge and the electrochemical reaction is highly reversible. This research broadens the thinking of exploring ZIBs cathode materials with good specific capacity and cycle performance.
Construction of hierarchical core-shell structured CoSe2@Fe3O4@Fe2O3 composite as advanced anodes for sodium ion batteries
Authors: Luo Shi , Chen Chenghao , Feng Ruojin , Chen Xuanjia , Chen Wenlin , Wu Zhangjie , Kong Xiangzhong
Published: September 2021

Transition metal selenides/oxides have received extensive attention, due to there suitable voltage plateaus and abundant reserves. However, intrinsic low electrons conductivity and huge volume change during sodiation/desodiation progress limit its wide application. To address these issues, CoSe2@Fe3O4@Fe2O3 with heterogeneous structure was successfully synthesized. As a SIBs anodes, the CoSe2@Fe3O4@Fe2O3 composite presents high electrochemical reversibility with a capacity of 360 mA h g−1 after 100 cycles at 100 mA g−1.
Distribution and Potential Ecological Risk Assessment of Four Light Rare Earth Elements in the Anning River Located in Sichuan Province, China
Authors: Wang X M , Hu J Z , Peng C , Wen W J , Ou H
Published: September 2021

In order to investigate the distribution of rare earth elements (REEs) in the Anning River, 48 surface water and 16 sediment samples were collected. The elements La, Ce, Pr and Nd were analyzed. Risk Quotient and Potential Ecological Risk index were used to assess the ecological risk in the Anning River. The results showed that total REEs concentrations (La, Ce, Pr, and Nd) varied from 1.43 μg/L to 24.30 μg/L in surface water, and from 74.86 mg/kg to 1542.16 mg/kg in sediments. Average RQ values displayed the order: Ce > La > Pr > Nd. The RQ values of all REEs exceeded 1 at 7 sites. In addition, the resulting RQ values for La were higher than 1 at 14 sites (87.50%). The average potential ecological risk of REEs in the Anning River indicated a high risk level (RI=44.40), mainly in sections S4-S6. The rare earth element Pr was the element that contributed the most to the Potential Ecological Risk index. Ecological risk should not be ignored. Thus, further studies are urgently required.
Mineralogical Study on the Consistency Property of Bentonite Mixed Soil
Authors: Okawara M , Saito Y , Ishiguro K , Hotta Y
Published: September 2021

Bentonite mixed soil, which is a mixture of bentonite with sand and gravel, can be easily compacted by adjusting the blending degree, and it is difficult for water to pass through and exhibits low permeability. It is widely used at construction sites because it can be mixed on-site and has good workability. Examples of its use include impermeable layers at waste disposal sites and measures to contain heavy metals from rocks generated from construction sites. The main component of bentonite is smectite, which is a swelling clay mineral, and the swelling property and consistency characteristics determine the engineering properties. In particular, low permeability is considered to be strongly influenced by the electrochemical properties at the crystal level peculiar to smectite. In this study, the mechanism of expression of engineering properties of bentonite mixed soil was investigated focusing on the mineralogy properties of smectite. Specifically, X-ray and near-infrared analysis were performed to clarify the crystal structure of smectite and the adsorptivity of water molecules. The change in interlayer distance were clarified by XRD. Information on the behavior of water molecules was obtained by NIR. From these analyses, we obtained information on the swelling, consistency and micro-physical properties of smectite, which is the main component of bentonite, related to water permeability.
Elution and Containment of Harmful Substances in Construction-Generated Soil: A Case Study of Oshikado Tunnel, Japan
Authors: Iwamoto Y , Shimizu Y , Morita S , Okawara M
Published: September 2021

In recent years, there has been an increasing number of cases in Japan where countermeasures against environmental pollution caused by natural heavy metals contained in soil and wastewater generated during construction work have become a problem. For example, when arsenic, which is often used, exceeds 0.01 mg/L, which is the criterion in the elution test, the generated soil is covered with low-permeability (permeability coefficient ≤1×10-6 cm/s) soil mixed with bentonite to prevent heavy metal leakage. Although the impact on the surrounding environment is predicted in the design of such a disposal site, it does not accurately reflect the behavior of leachate in the embankment and the elution characteristics of heavy metals. Therefore, in this study, for the purpose of optimal design of the disposal site, the distribution of heavy metals in the embankment, behavior of leachate, and elution amount of heavy metals were investigated, and a numerical analysis method using the advection-dispersion equation was examined. In addition, a large column test using soil at the site was conducted to reproduce the site. The parameters related to the permeation characteristics obtained from the column test agreed with the field test; however, the unit elution amount, which is a parameter related to the elution characteristics, was 7.5 times that of the field test. This result indicates the possibility of overestimating the elution amount of heavy metals in the test modeling of the disposal site.
Investigation of Penetration Process of Three Full-flow Penetrometers in Marine Soft Clay
Authors: Zhang H , Yang S F , Wang L
Published: September 2021

This study presents an experimental investigation of the penetration process in marine soft clay in the Shanghai coastal area using three types (non standard Ball (N), standard Ball(S) and T bar) of full-flow penetrometers. Three main factors (the penetration resistance, strength degradation, and strength factor) are evaluated and discussed in the comparative analysis of the penetration process. The results reveal that there is a model to predict the soil strength degradation in the range of low soil sensitivities (ST < 8). In particular, for the Ball(N) penetrometer, which is a non-standard penetrometer, the degradation process is more readily affected by the soil properties. For the Ball(S) and T bar penetrometers, the test results indicate a certain relationship between the soil sensitivity (ST) and the strength factors of undisturbed and remoulded soils with low sensitivity (ST < 8). however, this relationship is not observed with the Ball(N) penetrometer. These tests can enrich the application of conventional full-flow penetrometers in marine soft soils while facilitating the adaptation of non-standard penetrometers for in-situ tests in various soft soils.
Assessment of Heavy Metals in Mine Soil and Tailings from Jos, Nigeria
Authors: Olarinoye I O , Atipo M K , Awojoyogbe O B
Published: September 2021

Jos is a mining town in Nigeria; mining activities has been going on in the area for more than a 100 years. Although, the mining and other related activities have brought about economic, social growth and infrastructural development in the area. Unfortunately, mining activities has been linked to the enhance in the level of heavy metals in the soil and other geological formations in the environment. To ascertain the heavy metals (HM) burden in the soil due to tin mining activities at Rayfield-Du area of Jos, HM concentrations were evaluated in soil samples collected from the mine site. The HM concentrations in the soils were evaluated using the Energy Dispersive X-ray Florescence (EDXRF) spectrometer system. The analysis of eight HM (Cr, Co, Ni, Cu, Zn, As, Cd, and Pb) concentrations showed that they are above the Nigerian reference level except for Co and Ni. The pollution and ecological risk indices of the HM concentrations were classified as low for the mine soils.
The Ecological Variety Testing of Foreign Melon and Watermelon Hybrids in the Climatic Conditions of Southeastern Kazakhstan
Authors: Aitbayev T E , Mamyrbekov Zh Zh , Aitbaeva A T , Zorzhanov B D
Published: September 2021

The results of the ecological variety testing of melon and watermelon hybrids are presented in the paper. In the period from 2018 to 2020, 10 foreign varieties and hybrids of melon and watermelon were evaluated according to economic and valuable characteristics in the adaptation nursery in the climatic conditions of southeastern Kazakhstan. According to the set of qualities and indicators, 4 melon and watermelon varieties were distinguished and suggested for production.