bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the preparation of new biomass fuel based on fungus chaff of Auricularia auricula
Authors: Zuo Huimin , Zhang Peng , Liu Ao , Zhou Mingyuan
Published: July 2021

After saturated steam pretreatment and thermo-pressure drying, the moisture content decreased and the calorific value increased, thus the waste fungus chaff was transformed into new biomass energy. The physicochemical properties of the fungus chaff after thermo-pressure drying were tested to meet the standard of being used as biomass fuel. The experiment showed that: The thermo-pressure drying technology can stably reduce the moisture content of the fungus bran from more than 55% to less than 35%, and increase the received base calorific value from 4763.9kJ/kg to 12213.8kJ/kg, which meets the requirements of biomass power plants. The performance of volatiles, slagging property and other related fuels is improved, which lays an experimental foundation for the industrial implementation of biomass fuel.
Study on Flame Retardant of Environmentally Friendly HDPE Sheath Material
Authors: Yan-hui Zhong , Zhi-wen Qiu , Zi-hao Chen , Ya-lan Long
Published: July 2021

Magnesium stearate was used to modify the surface of aluminum hydroxide, and a composite system composed of magnesium stearate and red phosphorus was used to study the flame retardancy of HDPE sheath. By testing the oxygen index, impact strength, bending strength, melt flow rate and hardness of the composite, the results show that aluminum hydroxide and red phosphorus can play a synergistic effect of flame retardancy. With the increase of aluminum hydroxide content, when the content of aluminum hydroxide is 60 phr, the flame retardancy of the composite can reach UL94 V2 level, and the bending strength and hardness will also be improved, but the impact strength and melt flow rate decreased.
Effect of curing time on properties of polyether MDI polyurethane elastomer
Authors: Gang LU , Chang-geng Shuai , Xue Yang
Published: July 2021

In order to study the effect of curing time on the properties of polyurethane elastomers in MDI system and provide guidance for the production of polyurethane elastomers in this system, the effects of gradient (6-12h) curing time on the thermal stability and mechanical properties of polyurethane elastomers in polyether MDI system were studied in this paper. The results showed that the properties of polyurethane improved with the extension of curing time, and the mechanical properties of polyurethane tended to be stable when the curing time exceeded 10h.
Effects of Back-Reflectors on a-Si: H Solar Cells
Authors: Hu Zhihua , Aierken Abuduwayiti , Diao Hongwei
Published: July 2021

ZAO (ZnO: Al)/Al and ITO/Ag complex back-reflectors were successfully applied to substrate nip and superstrate pin amorphous silicon solar cells respectively. As a result, the short circuit current (Isc) for a cell with a complex back-reflector increases significantly as compared with a cell without a complex back-reflector. For a superstrate pin cell prepared on SnO2 coated glass, the short-circuit current even increases up to 30%.
Microstructure and Wear Resistance of Ni-Al2O3 Nano-composite Coating
Authors: Qu Guang , Wang Dongsheng , Wang Qunyou , Hua Mengzhang
Published: July 2021

Ni-Al2O3 nano-composite coating was prepared on the ASP30 powder metallurgical steel surface for semiconductor encapsulation mould by using electrodeposition method. Effects of Al2O3 contents on microstructure, microhardness and wear resistance of composite coating were analyzed. Results demonstrate that due to refined crystalline strengthening, dispersion strengthening and high-density dislocation strengthening of Al2O3 nanoparticles in uniform distribution, Ni-Al2O3 nano-composite coating has more compact structure and smaller grain size compared to the pure Ni coating, which are conducive to increase microhardness and wear resistance of the coating significantly. Neither too low nor too high Al2O3 contents is beneficial to improve microhardness and wear resistance of composite coating. The pure Ni coating has serious adhesion wearing, while the nano-composite coating with the moderate Al2O3 content has the best performance and it mainly has mild abrasive wear, accompanied with some adhesion wearing. Relatively serious adhesion wearing occurs on the wear surface of pure Ni coating. Differently, wearing surface of Ni-Al2O3 nano-composite coating is mainly dominated by mild abrasive wear, accompanied with some adhesion wearing. Neither too low and too high Al2O3 content is conducive to improve microhardness and wear resistance of composite coating.
Effects of Nb and Mo content on mechanical properties of Ti-Nb-Mo-Ta alloys by two-step pressure-free and hot isostatic pressing sintering
Authors: Li Huicong , Cai Qi , Liu Jinxu , Feng Xinya , Li Shukui
Published: July 2021

The Ti-(15-30) Nb-(2-11) Mo-3.5Ta (wt.%) alloys with the composition interval of 5.0 wt.% for Nb and 3.0 wt.% for Mo were prepared by a two-step sintering method from blended elemental powders. After pressure-free sintering and hot isostatic pressing, fully dense Ti-Nb-Mo-Ta alloys with favourable compressive properties were obtained, rendering the alloys suitable to be used as structural or biomedical materials. The phase constituent, microstructure, and compressive properties were investigated for these Ti-Nb-Mo-Ta alloys. With the increasing Nb or Mo content, the volume fraction of the α phase and the grain size of the β phase decreased. The yield strength of the Ti-Nb-Mo-Ta alloys first declined and then increased with the increase of Nb or Mo content. As for the strain at failure, it increased monotonously for the Ti-xNb-8Mo- 3.5Ta alloys with the addition of Nb, and it first increased and then decreased for the Ti-25Nb-yMo-3.5Ta alloys with the addition of Mo. After analysing and comparing the variation trend of volume fraction of α phase, grain size, yield strength and strain at failure, the dominant strengthening mechanisms of the Ti-xNb-yMo-3.5Ta alloys were interpreted. The dominating mechanism was second-phase strengthening for the alloys with lower alloying elements content, and it changed to solid solution strengthening with the increase of alloying elements content.
Measurement and Analysis of sliding bearing vibration
Authors: Kongxing Ding , Faxin Zhu , Qijiang Yang , Xianbin Teng , Junwei Zhang , Wenxiang Chen , Zhaojian Wang
Published: July 2021

In this paper, by changing the loading of sliding bearing and the analysis software of LMS_TEST. LAB modal tester, the vibration characteristics of sliding bearing are studied by using the cantilever sliding bearing test platform, and the experimental results are studied and analyzed. It is very important to study the vibration problem of the sliding bearing. The vibration test data of the sliding bearing under different rotating speeds are analyzed to control the vibration within the allowable range.
Numerical simulation of fatigue crack growth life of single side notched specimen
Authors: Wang Shuaiqiang , Zhirong WU
Published: July 2021

Under the action of cyclic load, fatigue fracture failure often occurs in many engineering structures during their services. Fatigue cracks in engineering structures begin to propagate under cyclic loading, and eventually lead to the failure of engineering structures. The study of fatigue crack is of great significance for evaluating the service life of engineering structures under cyclic loading. The prediction of fatigue crack growth life and path is the key problem of fatigue crack research. In this paper, the numerical simulation of fatigue crack growth of single side notched specimen is carried out by using the extended finite element method. According to the calculated stress intensity factor and the generalized Paris formula, the fatigue crack growth rate of single side notched specimen is obtained and the fatigue crack growth life is predicted. The results show that this method can effectively predict the fatigue crack growth life.
The Experimental Study on the Influence of Hydrogen Corrosion on the Crack Growth Rate of 45 Steel
Authors: Jing Wang , Kuichao Huang , Lei Dou
Published: July 2021

In order to comprehensively study the effect of hydrogen corrosion on the crack growth rate, 45 steel was used as a typical material in this paper and fatigue crack growth rate (FCGR) of under different corrosion conditions and different stress ratios at room temperature were tested. 9 groups of da/dN-Δढ curves were obtained and Paris expressions were fitted. The results show that under the experimental conditions of air and different concentrations of H2S corrosion environment, the value of parameter n of Pairs expression is basically stable at 3.5. Under the same stress ratio conditions, the FCGR of metals after H2S corrosion is greater than that of metals in the air environment, and it increases with the increase of corrosion concentration, Stress ratio affects FCGR greatly, and the effect of corrosion time is limited.
Application of Computer Vision and Image Processing for Micro Deformation
Authors: Xi Yujie
Published: July 2021

In this study, a micro deformation monitoring system was designed for metal plate based on computer vision. A rhombic mark on the aluminum plate was made to measure the micro deformation inside the aluminum sheet. For achieving high accuracy, the sub-pixel-level corner detection was applied to achieve the corner coordinates information of the mark. The micro deformation would be calculated in real deformation situation by using the proposed method. This monitoring system could be used in industrial production to detect whether samples slightly deformed.
Intelligent fault diagnosis of rolling bearing based on singular value decomposition
Authors: Shen Nanyan , Su Kun , Li Jing , Guo Jianrong , Li Xiaoying , He Tianqiang , Pu Junhao
Published: July 2021

In view of the scarcity of labeled fault samples in industrial scenarios and the difficulty of obtaining the size parameters of rolling bearings, this paper firstly combines the obtained averaged singular value (ASV) and ratio of neighboring singular values (NSVR) as a novel type of fault feature. Then K-means clustering method is used to classify feature vector ASV-NSVR automatically. The experimental results show that the proposed fault diagnosis method has a high recognition accuracy in the case of bad data.
Research on Risk Prediction of Train Derailment based on Relative Wheel-rail Displacement
Authors: Feifei Qin , Yu Dong
Published: July 2021

Derailment safety is the basis for safe train operation, and the derailment coefficient is an important indicator for judging whether a train is derailed. Traditional derailment coefficient prediction methods have problems such as high cost, low prediction accuracy, and the inability to monitor the contact status between wheels and rails of running trains in real time. This paper proposes a train derailment coefficient prediction method based on image processing. Firstly, use the generative adversarial network to extract the edge curve of the wheel-rail contact area. Secondly, determine the wheel-rail lateral relative displacement based on the positional relationship between the rail and the centerline of the wheelset. Use the speed and acceleration sensors to obtain the train speed, lateral acceleration, and longitudinal acceleration, and finally use improvements. The BP neural network integrates wheel-rail lateral displacement, speed, lateral acceleration, and longitudinal acceleration data to obtain the train derailment coefficient at the next moment. The field test results show that the derailment coefficient prediction model in this paper can achieve accurate prediction of the derailment coefficient and has good robustness.
Stress-strain Test of Exoskeleton Legs Based on Different Postures
Authors: Peng Xuefeng , Wang Kaiyuan , Dai Zongmiao , Liu Jiasheng
Published: July 2021

Aiming at the design requirements of high-strength and lightweight of exoskeleton leg materials, this paper designs a kind of exoskeleton leg mechanism made of T700 carbon fiber and TC4 titanium alloy. The mechanical properties of exoskeleton leg mechanism under three different postures of standing, stranding and squatting were tested by DH5921 dynamic strain gauge. The results showed that the maximum stress and strain were located at the ankle auricular part under three typical postures, and the maximum stress was 150.7MPa. The maximum strain value of the T700 composite material in the middle of the thigh is 848.05με, which meets the requirements of use. In the three different postures, the stress value of each place in the squatting posture increases obviously, but it is still far less than the required strength of the design material, and meets the requirements of use.
A research of action recognition based on attention mechanism
Authors: Zhang Ruoxi , She Jianan , Yu Li
Published: July 2021

To solve the problem of inadequate expression of action behavior features, this paper proposes an action recognition method based on attention mechanism. Firstly, in the feature extraction part, a CSE module is designed to model action features spatio-temporally, and then this module is incorporated into the residual network to improve the feature extraction ability of the model; after that, the LSTM network is used to solve the problem of temporal association of features; finally, the actions are classified by Softmax. The experimental results show that the improved recognition rates of this method on UCF101, HMDB51 and Kinetics400 datasets are 96.23%, 92.03% and 75.65%, respectively.
Research of semantic role labeling based on long short-term memory neural networks
Authors: Liang Xuheng
Published: July 2021

Semantic Role Labeling (SRL) is a shallow semantic analysis in the field of NLP, and a relatively basic and important step. Traditionally, SRL has been performed based on the results of syntactic analysis and has problems such as over-reliance on feature engineering. With the development of deep learning, many neural network models for NLP have been proposed and SRL tasks can be performed well by neural networks. Among these, long short-term memory networks form a very good fit with the SRL task by virtue of their sequence-based features. In this paper, in order, we first analyze the SRL task based on grammatical analysis and neural networks, then the SRL task based on LSTM and its improved models, then the dataset and model evaluation of the SRL task, and finally conclude and look forward.
Research on visual object tracking algorithm based on improved twin network
Authors: Dong-mei Shi , Xun Chen
Published: July 2021

The tracking accuracy of traditional algorithm decreases when the target is in a complex environment or the target itself changes, and an improved correlation filtering twin network algorithm combining the attention mechanism is proposed. Fast wavelet is used for filtering and multi-scale feature signal extraction, and loss function is used to minimize the squared error between sample and label. Then correlation filtering algorithm is used to calculate the similarity of image between target template and candidate region. Attention mechanism is introduced to improve correlation filtering twin network structure, and the GloU’s online learning is advanced as an aid to determine template updating. The experimental results show that the algorithm have certain improvement effect for target shade, quick movement and deformation problems, so performance and accuracy of target tracking, the algorithm has better competitiveness.
Selective Partial Update of NLMS Adaptive Filter Algorithm
Authors: Wang Weizhi , Li Jingyan , Li Mingdong
Published: July 2021

In view of the low convergence speed of the LMS algorithm and the high computational complexity of the NLMS algorithm in wireless communication system, a selective partial update NLMS algorithm is proposed. This algorithm only updates part of the filter coefficients instead of all filter coefficients during each adaptation. It effectively reduce the complexity of classic adaptive filtering algorithms. In this paper, a selective partial update of the NLMS algorithm is deduced, and the simulation verification is carried out to compare with the LMS algorithm and the NLMS algorithm, and the superiority of the algorithm is verified.
An Efficient Arrhythmia Classifier Using Convolutional Neural Network with Incremental Quantification
Authors: Huang Junguang , Liu Zijing , Liu Hao
Published: July 2021

Cardiovascular disease (CVD) is a dangerous disease, which can be effectively prevented by detecting arrhythmia early. In order to detect arrhythmia accurately, more and more researches use artificial intelligence methods to realize the classification and detection of electrocardiogram (ECG) signals. However, most of these designs are unfriendly to the hardware design due to too many parameters which lead to large calculation power and data accessing power. In this paper, we present an efficient arrhythmia classifier based on the convolutional neural network with the incremental quantification. This more efficient design can classify ECG signals accurately with lower capacity of parameters. The simulation results show that the recognition rate of the network with the incremental quantification has reached 92.76% with 39.34KB memory footprint, which is beneficial to hardware design and has better accuracy than other advanced quantification methods.
Abnormal heart rate detection based on double slope QRS beat location
Authors: Zhang Yiheng , Guo Bin , Zhang Hongyuan , Sun Jianan
Published: July 2021

In order to improve the accuracy and reliability of abnormal heart rate detection, a method of abnormal heart rate detection based on double slope QRS beat location is proposed. Firstly, according to the singularity of QRS wave, the slope difference between the left and right sides is used for localization, and double thresholds are set to track the real-time change of the signal to ensure the robustness of localization. Secondly, wavelet coefficients are extracted as beat frequency features by wavelet transform. Finally, XGBoost algorithm is used for classification. In the case of the same data set, compared with the existing arrhythmia detection algorithm, the performance is further improved. The sensitivity of QRS detection is 99.65%, the positive prediction rate is 99.41%, and the accuracy of heart rate anomaly classification is 99.12%. This method can locate the beat more effectively, which provides a new method for the research of abnormal heart rate detection.
Millimeter-Wave Radar and Video Fusion Vehicle Detection based on Adaptive Kalman Filtering
Authors: Wang Qian , Song Yansong , Xu Dongpo
Published: July 2021

Road traffic safety has always been the focus of social concern, and the actual road traffic scenes, where only a single sensor is applied cannot cope with the interference brought by complex external factors, which makes vehicle detection extremely challenging. This paper focuses on a vehicle detection algorithm for the fusion of millimeter-wave radar sensor and monocular camera sensor, including the calibration of millimeter-wave radar and camera, the establishment of a temporal fusion model of the two sensors. Finally, the target information obtained from the two sensors is fused with the data using the adaptive Kalman filter fusion algorithm, which can reduce data ambiguity and increase the reliability and validity of the data. Experiments show that the method can overcome the shortcomings of single sensor in target detection, and the obtained target information is more comprehensive compared with the monocular camera detection results.
EEG Emotion Recognition Based on Optimal Feature Selection
Authors: Ma Xin , Liu Peng , Wang Xuemeng , Bai Xuemei
Published: July 2021

Aiming at the problems of dimensional disasters and low classification accuracy caused by too many features extracted in the emotion recognition process, an EEG emotion recognition method with optimized feature selection is proposed. The individual rhythmic signals of the EEG are obtained by wavelet packet decomposition and the sample entropy, energy and power spectral density are extracted as EEG features. A discrete binarization of the feature matrix using the Beetle Antennae Search (BAS) algorithm, while introducing a subset of features into the objective function and searching for the optimal subset of features. Finally, the SVM classifier is used for classification. The experimental results show that it achieves 89.72% accuracy on the DEAP dataset and significantly reduces the original feature dimension compared with the traditional feature selection method, which has good application prospect.
Research on 5G Security Technology for Industrial Internet
Authors: Zhao Zichen
Published: July 2021

5G network has great application potential in the field of industrial Internet. However, the current lack of development of 5G network in the field of security technology restricts its application on the Industrial Internet. In this article, the author combines the industry’s needs for Industrial Internet security, and summarizes the research status of 5G network security technology, gives the development direction of three 5G network security technologies with development potential. This paper found that due to the three end-to-end characteristics of the Industrial Internet: physical security, information security, and system self-healing, there are security requirements; the other three 5G network security technologies, namely lightweight encryption mechanism, physical layer security technology and network slicing security technology will help 5G network be more widely used in the Industrial Internet field.
LAENet: Light-weight asymmetric encoder-decoder network for semantic segmentation
Authors: Hong Liangyi , Duan Shukai , Wang Lidan , Pan Yongbin
Published: July 2021

Encode-decoder structure is used in deep learning for real-time dense segmentation task. On account of the limitation of calculation burden on mobile devices, we present a light-weight asymmetric encoder-decoder network in this paper, namely LAENet, which quickly and efficiently accomplish the task of real-time semantic segmentation. We employ an asymmetric convolution and group convolution structure combined with dilated convolution and dense connectivity to reduce computation cost and model size, which can guarantee adequate receptive field and enhance the model learning ability in encoder. On the other hand, feature pyramid networks (FPN) structure combine attention mechanism and ECRE block are utilized in the decoder to strike a balance between the network complexity and segmentation performance. Our approach achieves only have 0.84M parameters, and is able to reach 66 FPS in a single GTX 1080Ti GPU. Experiments on Cityscapes datasets demonstrate that superior performance of LAENet is better than the existing segmentation network, in terms of speed and accuracy trade-off without any post-processing.
Design and characterization of Kerberos: a 48-channel analog pulse processing and data acquisition platform
Authors: King P. , Gugiatti M. , Carminati M. , Buonanno L. , Borghi G. , Pepponi G. , Lechner P. , Siegmann D. , Urban K. , Houdy T. , Mertens S. , Fiorini C.
Published: July 2021

A multi-channel data processing and acquisition system based
on an analog ASIC (SFERA) has been designed and realized. The
platform, called Kerberos, is suitable for the readout of large
arrays of Silicon Drift Detector (SDD) for X-ray, γ-ray and
electron spectroscopy applications. Each one of its 48 inputs is
equipped with a 9th order semi-Gaussian shaping
amplifier with programmable peaking time (0.5, 1, 2, 3, 4 and 6
). The pulse amplitudes are multiplexed into three 16-bit
high linearity SAR ADCs and digitized into an Artix-7 FPGA
module. Kerberos will be used for the characterization of monolithic
SDD matrices for the TRISTAN project. Many different readout
strategies can be selected on Kerberos Graphic User Interface: for
TRISTAN it has been decided to use a full detector readout strategy,
with maximum input throughput of about 166 kcount/s. This work
presents a full characterization of this scalable platform and its
use with several detectors types (SDD, micro-strips) in X-ray, gamma
and beta spectroscopy.
The effects on public health of climate change adaptation responses: a systematic review of evidence from low- and middle-income countries
Authors: Scheelbeek Pauline F D , Dangour Alan D , Jarmul Stephanie , Turner Grace , Sietsma Anne J , Minx Jan C , Callaghan Max , Ajibade Idowu , Austin Stephanie E , Biesbroek Robbert , Bowen Kathryn J , Chen Tara , Davis Katy , Ensor Tim , Ford James D , Galappaththi Eranga K , Joe Elphin T , Musah-Surugu Issah J , Alverio Gabriela Nagle , Schwerdtle Patricia Nayna , Pokharel Pratik , Salubi Eunice A , Scarpa Giulia , Segnon Alcade C , Siña Mariella , Templeman Sienna , Xu Jiren , Zavaleta-Cortijo Carol , Berrang-Ford Lea
Published: July 2021

Climate change adaptation responses are being developed and delivered in many parts of the world in the absence of detailed knowledge of their effects on public health. Here we present the results of a systematic review of peer-reviewed literature reporting the effects on health of climate change adaptation responses in low- and middle-income countries (LMICs). The review used the ‘Global Adaptation Mapping Initiative’ database (comprising 1682 publications related to climate change adaptation responses) that was constructed through systematic literature searches in Scopus, Web of Science and Google Scholar (2013–2020). For this study, further screening was performed to identify studies from LMICs reporting the effects on human health of climate change adaptation responses. Studies were categorised by study design and data were extracted on geographic region, population under investigation, type of adaptation response and reported health effects. The review identified 99 studies (1117 reported outcomes), reporting evidence from 66 LMICs. Only two studies were ex ante formal evaluations of climate change adaptation responses. Papers reported adaptation responses related to flooding, rainfall, drought and extreme heat, predominantly through behaviour change, and infrastructural and technological improvements. Reported (direct and intermediate) health outcomes included reduction in infectious disease incidence, improved access to water/sanitation and improved food security. All-cause mortality was rarely reported, and no papers were identified reporting on maternal and child health. Reported maladaptations were predominantly related to widening of inequalities and unforeseen co-harms. Reporting and publication-bias seems likely with only 3.5% of all 1117 health outcomes reported to be negative. Our review identified some evidence that climate change adaptation responses may have benefits for human health but the overall paucity of evidence is concerning and represents a major missed opportunity for learning. There is an urgent need for greater focus on the funding, design, evaluation and standardised reporting of the effects on health of climate change adaptation responses to enable evidence-based policy action.
Theology of disaster: a study on west bandung people’s responses to the potency of earthquake
Authors: Kosasih A , Surahman C , Yuniartin T , Firmansyah M I
Published: July 2021

This article deals with the beliefs living among societies in Indonesia. These beliefs are studied through the responses of West Bandung people to the potency of earthquake. Geographically, West Bandung area is located in the ring of fire where natural calamities potentially could occur. These responses shed light varied beliefs and theological perspectives of people. This study belongs to qualitative research. However, the reseachers also use questionnares, Through data collection and analysis, the researchers conclude that West Bandung people are religious (they see the earthquake by religious meaning and explanation where they regard natural disaster as God’s decree and will, God’s testing, therefore they have to be patient and repent to God). However, they also look it as natural phenomenon which can be observed by scientific approach. In term of Islamic theology, The people are close to tradisional theology, especially Asy’ariyah school of Islamic theology. However, this reseach shows the religious pattern of contemporary Indonesia where the grouping to certain theological school seems irrelevant. Due to the diversity of religious authorities and sources of knowledge, the pattern of religiosity of society is now no longer leading to a particular school of thought, but rather shows a hybrid pattern (hodgepodge).
Impact of the Electromagnetic Environment on UAV’s Datalink
Authors: Bennageh I. , Mahmoudi H. , Labbadi M.
Published: July 2021

The deployment of drones for any mission relies heavily on a ground control system. The UAV must therefore maintain a stable datalink with the ground control station to allow it to be controlled in real time by the ground operator. The evolution of drones in specific electromagnetic environments can seriously compromise data linkage, giving rise to electromagnetic susceptibility (EMS) issues. This article presents a review of the exploratory literature of electromagnetic interferences that the datalinks between UAVs and the ground station can face from the point of view of electromagnetic compatibility (EMC). The goal is to understand the effects of a given EM environment on the datalinks of an UAV system in order to predict its behaviour and perform the necessary precautions and improvements.
Power Sharing of Grid-connected AC Microgrid by A Simplified Distributed Control
Authors: Guo Shuping , Cai He
Published: July 2021

The power sharing problem is one of the core problems for microgrid control. By designing an elegant command generator, the power sharing problem for a grid-connected microgrid has been converted into a tracking problem for an interconnected leader-follower multiagent system, and was solved by a distributed control law. In this paper, we further consider the same tracking problem. By utilizing Lyapunov analysis, we have shown that a simplified version of the existing control law can still solve the same problem. Numerical simulations are provided to validate this result.
A supplementary subsynchronous Damping Controller to damp Subsynchronous Oscillation in Muti-infeed LCC-HVDC system
Authors: Hu Sile , Zhen Zijing
Published: July 2021

As more and more clean energy sources are integrated to the power system through HVDC transmission system, two or more LCC-HVDC system will feed in to the same system forming multi-feed LCC-HVDC system. The inverters of different LCC-HVDC systems may interact with each other to cause subsynchronous oscillation. Firstly, a muti-input muti-output interconnected model with variable speed is established to investigate the cause of the oscillation. Secondly, a supplementary subsynchronous damping controller (SSDC) on each LCC-HVDC system is designed to damp the oscillation. At last, a small test system with two LCC-HVDC systems is used to verify the effectiveness of the controllers.
Target Positioning Optimization Method in Power System
Authors: Ba S , Hou Z B , Wang D W , Shi G Y , Zhang W H , Han X J , Dong C Y , Liu J J
Published: July 2021

This thesis presents a method that a position measurement method for moving targets is proposed based on the positioning method based on the time difference of arrival (TDOA) which is based on the research on the positioning problem of station inspection operators and equipment in complex working conditions. The probability error method is introduced to optimize the traditional positioning method that realizes the target node positioning by optimizing the distance difference between the target node to be located in the network domain environment and different base stations, which can effectively improve the positioning accuracy of staff and equipment in the station. Through experiments in a complex power frequency electric field environment, the test results show that the results calculated by the optimization method are better than the existing traditional positioning methods, and can effectively improve the positioning accuracy under the condition of line-of-sight, and realize the substation space Mobile target positioning to ensure the safety of operators.
Construction of BiOBr0.5Cl0.5 heterojunctions for photocatalytic treatment of waste drilling fluid in oilfield
Authors: Li Yizheng , Jiang Guancheng , Dong Tengfei , Li Xiaoqing , Yang Lili
Published: July 2021

Drilling fluid is very essential for oil and gas drilling process. However, the treatment of the waste drilling fluid becomes an urgent issue because of the large amount and the lack in effective degradation method. Photocatalysis as an advanced strategy to solve the environmental pollution, has drawn widely attention. In this contribution, BiOBr0.5Cl0.5 heterojunctions are constructed through a hydrothermal method to act as a photocatalyst for photocatalytic degradation of waste drilling fluid. The successful construction of BiOBr0.5Cl0.5 heterojunctions is confirmed by XRD, SEM, EDS, and BET analysis and the results show that BiOBr0.5Cl0.5 is not a simple mechanical mixture. These heterojunctions in synthesis of photocatalyst is conducive to the photoactivity, which would lead to relatively high surface area and pore width in photocatalyst. It is found that photocatalytic degradation over BiOBr0.5Cl0.5 is a feasible approach for solving waste drilling fluid pollution. From the results of evaluation experiments, it can be seen that the colored materials and macromolecular organic polymers can be both degraded by BiOBr0.5Cl0.5. The presence of Br and Cl in the composite could promote the effective separation of photogenerated carriers and the construction of the active species ·O2- and ·H+, enhancing the photocatalytic activity of BiOBr0.5Cl0.5 heterojunctions. Given that the outstanding performance in degrading RhB or HPAM and the sustainability of BiOBr0.5Cl0.5, The photocatalytic offers a promising reference to the treatment of waste drilling fluid.
Numerical simulation of stress field distribution before re-fracturing treatment
Authors: Liu Xiaoqiang , Qu Zhanqing , Guo Tiankui , Huang Wenjie
Published: July 2021

Due to the first fracturing failure at the middle and final stages of oil and gas field development, re-fracturing technology has become a key method to increase production in oilfield. So, stress field distribution should be the key successful factor to impact re-fracturing technology after the initial fracturing in reservoir. In order to accurately describe the initial stress field distribution of reservoir after fracturing and provide theoretical basis for subsequent re-fracturing, this paper with theory of rock fracture mechanics and fluid-solid coupling equation had built several ABAQUS numerical model of hydraulic fracturing according to the basic theory of XFEM, to analyses the stress influence by horizontal stress difference, rock elastic modulus, Poisson’s ratio and production time before re-fracturing. Numerical simulation results show that due to the initial crack and the change of pore pressure in the process of production, the direction and size of the original stress field change a lot, which lead a stress field redirection; Reservoir and rock physical mechanical parameters bring a significantly change of reservoir stress field distribution; with the difference of horizontal stress, rock elastic modulus and oil field production time increasing, induced stress effect and stress redirection area decrease; the greater of Poisson’s ratio, the induced stress effect and redirection area is smaller.
The Impact of Surface Characteristics of Slightly Soluble Cu (II) and Ni (II) Compounds on their Electroflotation Extraction from Concentrated Solutions of Electrolytes
Authors: Brodskiy V A , Malkova Yu O , Il’yin V I , Soboleva V A
Published: July 2021

The impact of concentrated NaCl, NaNO3, and Na2SO4 solutions on the average hydrodynamic diameter and charge of particles of slightly soluble nickel and copper compounds were found to be rather identical. In electrolytes solutions, the average size of the dispersed phases particles decreased from 50–54 µm to 30–45 µm, the electrokinetic potential became more negative (-(2–10) mV). In a result, the removal of slightly soluble nickel and copper compounds decreased from 98% to 94–97% and 30–94%, respectively. Minimal efficiency of electroflotation-based extraction of nickel was observed in the presence of NaNO3. Cationic flocculants promoted increased extraction up to 98–100% regardless of the electrolyte, and decreased electroflotation duration from10–15 min to 5–7 min.
Analysis of Soft Story and Torsional Irregularity Factors in the Seismic Performance of Reinforced Concrete Buildings by Nonlinear Static Analysis
Authors: Lagos W A , Blas O E , Orihuela J
Published: July 2021

The seismic design of irregular buildings is usually developed using an irregularity factor according to its nature. However, seismic stresses are impacted as the irregularity approaches the extreme limit. In this study, we analyzed the soft story and torsional irregularity factors of reinforced concrete structures with structural system: frame, dual and structural walls of 5, 7 and 10 floors respectively. To this end, a Nonlinear Static Analysis (NLS) - Pushover was carried out. This analysis is carried out in two stages. First, a regular structure is analyzed in plan and in elevation, which is the regular model. Second, the geometry of the regular structure is modified in plan and in elevation in order to perform the same analysis, so as to show irregularity due to soft story and torsion. The purpose is to obtain the structural response with variations of both irregularities from minor to major. Lastly, the seismic stresses obtained from the irregular models are compared with the regular model response, and then, new irregularity factors are proposed for the cases studied.
Problem analysis of residential buildings in Armenia in view of green architecture concept
Authors: Papoyan Atanes , Zhan Changhong , Han Xueying
Published: July 2021

Green buildings starting to become an unavoidable trend due to the introduction of an assessment standard for green construction in Armenia. In the world green residential buildings grow even faster than green public buildings. The total area of residential buildings is approximately two times higher than in public buildings. In this work is eliminated the main problems of residential building in Armenia, in socio-demographic, functional, psychological, economical and technical aspects.
Blasting Excavation Induced Damage Caused to the Rock Mass Surrounding Tunnels
Authors: Lai J , Wang Y C , Liu Y
Published: July 2021

Multi-hole blasting is often used for tunneling, however, blasting can damage the surrounding rock. To study the effect of blasting on surrounding rock and the damage caused, this paper presents an equivalent load method and a damage constitutive model of surrounding rock, based on earlier works and existing literature. A numerical simulation method is adopted to predict the most vulnerable part of the surrounding rock in the tunnel under blasting load. The research results have certain guiding significance for tunnel construction.
Difference-frequency generation in an AlGaAs Bragg-reflection waveguide using an on-chip electrically-pumped quantum dot laser
Authors: Schlager A , Götsch M , Chapman R J , Frick S , Thiel H , Suchomel H , Kamp M , Höfling S , Schneider C , Weihs G
Published: July 2021

Nonlinear frequency conversion is ubiquitous in laser engineering and quantum information technology. A long-standing goal in photonics is to integrate on-chip semiconductor laser sources with nonlinear optical components. Engineering waveguide lasers with spectra that phase-match to nonlinear processes on the same device is a formidable challenge. Here, we demonstrate difference-frequency generation in an AlGaAs Bragg reflection waveguide which incorporates the gain medium for the pump laser in its core. We include quantum dot layers in the waveguide that generate electrically driven laser light at ∼790 nm, and engineer the structure to facilitate nonlinear processes at this wavelength. We perform difference-frequency generation between 1540 nm and 1630 nm using the on-chip laser, which is enabled by the broad modal phase-matching of the AlGaAs waveguide, and measure normalized conversion efficiencies up to (

0.64
±
0.21

)% W−1 cm−2. Our work demonstrates a pathway towards devices that utilize on-chip active elements and strong optical nonlinearities to enable highly integrated photonic systems-on-chip.
Room temperature ppt-level NO2 gas sensor based on SnO
x
/SnS nanostructures with rich oxygen vacancies
Authors: Tang Hongyu , Gao Chenshan , Yang Huiru , Sacco Leandro , Sokolovskij Robert , Zheng Hongze , Ye Huaiyu , Vollebregt Sten , Yu Hongyu , Fan Xuejun , Zhang Guoqi
Published: July 2021

In this paper, tin oxidation (SnO
x
)/tin-sulfide (SnS) heterostructures are synthesized by the post-oxidation of liquid-phase exfoliated SnS nanosheets in air. We comparatively analyzed the NO2 gas response of samples with different oxidation levels to study the gas sensing mechanisms. The results show that the samples oxidized at 325 °C are the most sensitive to NO2 gas molecules, followed by the samples oxidated at 350 °C, 400 °C and 450 °C. The repeatabilities of 350 °C samples are better than that of 325 °C, and there is almost no shift in the baseline. Thus this work systematically analyzed the gas sensing performance of SnO
x
/SnS-based sensor oxidized at 350 °C. It exhibits a high response of 171% towards 1 ppb NO2, a wide detecting range (from 1 ppb to 1 ppm), and an ultra-low theoretical detection limit of 5 ppt, and excellent repeatability at room temperature. The sensor also shows superior gas selectivity to NO2 in comparison to several other gas molecules, such as NO, H2, SO2, CO, NH3, and H2O. After x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron
microscopy, transmission electron microscope, and electron paramagnetic resonance characterizations combining first principle analysis, it is found that the outstanding NO2 sensing behavior may be attributed to three factors: the Schottky contact between electrodes and SnO
x
/SnS; active charge transfer in the surface and the interface layer of SnO
x
/SnS heterostructures; and numerous oxygen vacancies generated during the post-oxidation process, which provides more adsorption sites and superior bandgap modulation. Such a heterostructure-based room-temperature sensor can be fabricated in miniaturized size with low cost, making it possible for large-scale applications.
Continuum time-delayed electron hopping in the extended dynamical molecules and entropy-ruled Einstein relation for organic semiconductors
Authors: Navamani K
Published: July 2021

Charge transport (CT) in dynamically disordered molecular systems is still unclear; though it is fundamentally important to understand the semiconducting properties of molecular devices. In this regard, we explore vibronically coupled polaron hopping transport in the extended hopping systems (N + 1 sites) of thiazolothiazole (TZTZ) based molecules. The molecular vibrations correlated charge transfer integral and site energy fluctuation effects on polaron transport are analyzed by kinetic Monte-Carlo simulations. In order to quantify the CT properties more precisely, we have proposed the continuum time delayed CT mechanism, which takes account of typical disordered (static or dynamic) effect via dispersion on each CT quantity (like charge transfer rate, diffusion coefficient, mobility, current density and etc) at each hopping. The charge compressibility analysis further addresses the electronic level understanding of all CT quantities, which originally relates the thermodynamic density of states with CT. Using differential entropy-dependent charge density and diffusion expressions, the drift-diffusion transport has been elucidated for different extended systems of TZTZ derivatives. Besides, we have mainly developed entropy-ruled diffusion-mobility relation for both degenerate and nondegenerate materials to study the validity and limitations of original Einstein relation, which directly pertain to the device performance. Here, the traversing chemical potential along the hopping sites is the deterministic parameter of diffusion-mobility ratio. Using our continuum time delayed model, we can categorize the typical disordered transport in the molecular semiconductors; whether is dynamic or static or intermediate disordered transport.
Integrated farm management systems to improve nutrient management using semi-virtual Farmlets: agronomic responses
Authors: Li Carson , Hunt Derek , Koenig Karen , Smukler Sean , Bittman Shabtai
Published: July 2021

With increasing demand for land and food, there is growing interest in sustainable intensification of agricultural production. Here we investigated sustainable intensification of grass and corn production for dairy farms using a system of semi-virtual farmlets that combine replicated field research plots with feed modelling. We improved manure N capture by spreading separated liquid fraction with a low emission sliding shoe applicator on grass, and manure P capture by precision injecting separated sludge into corn. Reducing the number of annual harvests (5 to 3) increased grass yield and inter-seeding Italian ryegrass in early maturing corn increased fall growth of the cover crop, thus helping to protect soil over winter and providing additional high quality herbage in spring. Irrigation improved yield and potentially yield stability of corn and grass, and adding a nitrification inhibitor to reduce N2O emission may help reduce pollution swapping especially from injected manure. Overall, allocating more land to corn than grass will increase farm productivity but effectiveness of measures to reduce pollution and pollution swapping need to be evaluated. Results show that good practices ensuring vigorous crops are challenging to implement but critical for achieving sustainable intensification. The semi-virtual farmlet system is very helpful for developing and evaluating sustainable production measures for corn and grass.
Littlewood complexes for symmetric groups
Authors: Ryba Christopher
Published: July 2021

We construct a complexL∙λ\mathcal {L}_\bullet ^\lambdaresolving the irreducible representationsSλ[n]\mathcal {S}^{\lambda [n]}of the symmetric groupsSnS_nby representations restricted fromGLn(k)GL_n(k). This construction lifts toRep(S∞)\mathrm {Rep}(S_\infty ), where it yields injective resolutions of simple objects. It categorifies stable Specht polynomials, and allows us to understand evaluations of these polynomials for allnn.