bluuebunny/crossref_metadata_2025 huggingface dataset:
Geodesic equation in non-commutative gauge theory of gravity*
Authors: Touati Abdellah , Zaim Slimane
Published: June 2022

In this study, we construct a non-commutative gauge theory of the modified structure of the gravitational field using the Seiberg-Witten map and the general tetrad fields of Schwarzschild space-time to show that the non-commutative geometry removes the singularity at the origin of the black hole, thus obtaining a non-singular Schwarzschild black hole. The geodetic structure of this black hole presents new types of motion next to the event horizon within stable orbits that are not allowed by the ordinary Schwarzschild spacetime. The noncommutative periastron advance of the Mercury orbit is obtained, and with the available experimental data, we find a parameter of non-commutativity on the order of

. This result shows that the new fundamental length,

, is on the order of

.
Human-in-the-loop optimization of visual prosthetic stimulation
Authors: Fauvel Tristan , Chalk Matthew
Published: June 2022

Objective. Retinal prostheses are a promising strategy to restore sight to patients with retinal degenerative diseases. These devices compensate for the loss of photoreceptors by electrically stimulating neurons in the retina. Currently, the visual function that can be recovered with such devices is very limited. This is due, in part, to current spread, unintended axonal activation, and the limited resolution of existing devices. Here we show, using a recent model of prosthetic vision, that optimizing how visual stimuli are encoded by the device can help overcome some of these limitations, leading to dramatic improvements in visual perception. Approach. We propose a strategy to do this in practice, using patients’ feedback in a visual task. The main challenge of our approach comes from the fact that, typically, one only has access to a limited number of noisy responses from patients. We propose two ways to deal with this: first, we use a model of prosthetic vision to constrain and simplify the optimization. We show that, if one knew the parameters of this model for a given patient, it would be possible to greatly improve their perceptual performance. Second we propose a preferential Bayesian optimization to efficiently learn these model parameters for each patient, using minimal trials. Main results. To test our approach, we presented healthy subjects with visual stimuli generated by a recent model of prosthetic vision, to replicate the perceptual experience of patients fitted with an implant. Our optimization procedure led to significant and robust improvements in perceived image quality, that transferred to increased performance in other tasks. Significance. Importantly, our strategy is agnostic to the type of prosthesis and thus could readily be implemented in existing implants.
Dislocation structure of tungsten irradiated by medium to high-mass ions
Authors: Wielunska B. , Płociński T. , Schwarz-Selinger T. , Mayer M. , Jacob W. , Ciupiński L.
Published: June 2022

Single crystalline tungsten was irradiated by the medium-mass ion Si with 7.5 MeV and high mass-ion W with 20.3 MeV up to a calculated peak damage level of 0.04 dpa and 0.5 dpa. The obtained dislocation structure of the damage zone was investigated by transmission electron microscopy and systematically compared with each other. Bright-field kinematical images were taken under four different two-beam diffraction conditions g = −200, 020, −110, 110 close to the [100] zone axis. The observed damage depth and damage peak position is in good agreement with the SRIM calculated damage depth profiles. The dislocation structures were investigated at the region of the damage peak because there the damage levels are comparable. In both irradiations (Si and W), the dislocation structures were similar. At the low damage level of 0.04 dpa dislocation loops and dislocation-loop clusters were found. The size of the dislocation loops in the W-irradiated tungsten sample was up to 20% higher than for the Si-irradiated sample. At the high damage level of 0.5 dpa a dislocation network consisting of dislocation-loop chains and dislocation lines was found for both irradiations. The dislocation line density was about 12% higher for the W-irradiated sample. Through comparison of the damage zone to SRIM damage depth profiles it was found that the transition from dislocation loops and dislocation-loop clusters to an ordered dislocation network takes place at about 0.08–0.1 dpa. Despite the large differences in ion mass and irradiation energy the dislocation structures were very similar.
5G and Beyond Networks for 3D MIMO Using Artificial Intelligence in 5G Network
Authors: Yadav Ranjeet , Tripathi Ashutosh , Pathak Sunil , Singh Gill Harjot
Published: June 2022

Today’s wireless systems would be incomplete without MIMO systems, which have become increasingly common in recent years due to their ability to increase both spectrum efficiency and energy efficiency at a significant rate. Prior MIMO, the most often utilised system was a single-input, single-output system, which had limited capability and could not reliably support a huge number of users. Throughout this study, an artificial intelligence machine training MIMO channel is developed to handle the huge customer demand.. However, the ever-increasing needs are not met by this new technology. AI techniques becoming more prominent in determining the angle of elevation and angle of arrival for 3D MIMO in 5G system. These days, more and more people are using wireless devices, and these devices generate an enormous volume of information that must be processed quickly and reliably. AI based machine learning solve the issue and provide more throughput and energy efficient 5G system.
Development of an optimal operating policy of multi-reservoir systems in Mahanadi Reservoir Project Complex, Chhattisgarh
Authors: Shashikant Verma , Sahu Ramgopal T. , Prasad A.D. , Verma Mani Kant
Published: June 2022

Real-world optimization problems are usually non-linear and solving nonlinear problems requires time. Hence heuristic techniques are frequently used. Simulated annealing (SA) is one of the most commonly used heuristic algorithms. SA is useful in the narrow search area. In the present study, simulated annealing has been developed to derive the optimal for multi-reservoir systems. Problem statement: In respect of water release, multi-reservoir system in Mahanadi Reservoir Project is an example of such a complex system, therefore the optimum operation of such a reservoir is one of the complicated and uncertainxs issues water resource management. Approach: Traditional models to optimize water resource systems have proven to be ineffective due to increased decision variables and time constraints. In recent decades, the adaptive random research SA model has shown acceptable performance in solving major problems. Results: The model applies to derive the optimal operating policies of existing multi-reservoirs system in Chhattisgarh, India. The formulated objective function of the present study is to minimize the sum of squared deviation on downstream release and demand and compare the performance of the SA model to the existing reservoir systems operation policy. The overall performance of existing multi-reservoir system has increased on average by, 28.09%, 10.12%, 36.49% in case of reliability, resilience, sustainability respectively, and vulnerability reduced up to 11.83%. Conclusions/Recommendations: The results of these algorithms show that SA can deal with complex problems. SA is a novel promising reservoir optimization search technique. It merits further research for other applications in this field.
Crowd behavior anomaly detection using correlation of optical flow magnitude
Authors: Chakole Pallavi D , Satpute Vishal R , Cheggoju Naveen
Published: June 2022

Nowadays, crowd monitoring is a contentious issue. Because of the increasing population and diversity of human activities, crowd scenarios in the real world are becoming more common, demanding the need for an automotive anomaly detection system. Crowd behavior is influenced by the thoughts and attitudes of others around them. An unexpected event can turn a peaceful crowd into a riot. A mechanism based on optical flow must be implemented to compensate for all of these factors. The amount of motion present in two successive frames is estimated using optical flow. It includes information on velocity in the x & y plane, along with magnitude and line of action. By means of “anomalous event” in this paper is quick and sudden dispersal of the crowd. For detecting an event the magnitude of two successive frames should be taken into account followed by estimating a correlation. We expect a high correlation, slight motion, and low rate of change in velocities at non-anomalous events, but as soon as an anomalous event occurs, the correlation begins to decrease with a significant change in velocity and large motion vectors. The methodology was tested on a dataset from the University of Minnesota that included 11 movies from three different circumstances. Almost all anomalous occurrences in videos were successfully detected using this method.
A TinyML Approach to Human Activity Recognition
Authors: Gupta Shubham , Jain Dr. Sweta , Roy Bholanath , Deb Abhishek
Published: June 2022

Human Activity Recognition has been a favorite topic for the scholars not only because of its wide scale acceptance in the industry but areas which may help in medical and in our normal household works as well. Since to make this technology available to the last person standing in the queue it is important that models compiled and trained in this field are not just high performing but optimized as such with incurs the least overhead. And thus bringing TinyML into the picture which has specialty in the field of optimizing the model w.r.t. the size of the model, energy consumption, network bandwidth usage etc. Thus this work includes using optimizing techniques such as pruning and quantization on the pre-proposed models and analyze the changes it causes in such models w.r.t accuracy and size. Our work is able infer that by using both Pruning and Quantization techniques on a human activity recognition model we can compress a model up to 10 time without hampering severe diversion to the accuracy of the model. We have taken three models and UCI-HAR dataset and compare the outcomes of the experiment.
Deep Learning (CNN) and Transfer Learning: A Review
Authors: Gupta Jaya , Pathak Sunil , Kumar Gireesh
Published: June 2022

Deep Learning is a machine learning area that has recently been used in a variety of industries. Unsupervised, semi-supervised, and supervised-learning are only a few of the strategies that have been developed to accommodate different types of learning. A number of experiments showed that deep learning systems fared better than traditional ones when it came to image processing, computer vision, and pattern recognition. Several real-world applications and hierarchical systems have utilised transfer learning and deep learning algorithms for pattern recognition and classification tasks. Real-world machine learning settings, on the other hand, often do not support this assumption since training data can be difficult or expensive to get, and there is a constant need to generate high-performance beginners who can work with data from a variety of sources. The objective of this paper is using deep learning to uncover higher-level representational features, to clearly explain transfer learning, to provide current solutions and evaluate applications in diverse areas of transfer learning as well as deep learning.
Green synthesis of silver nanoparticles from anthocyanin extracts of purple cabbage (brassica oleracea var capitata) and its characteristics for dye-sensitized solar cells (DSSC) application
Authors: Arsyad Waode Sukmawati , Cassandra Febryanti , Asharuddin Muh , Suere Suryani , Ramadhan La Ode Ahmad Nur , Hidayat Rahmat
Published: June 2022

We extracted natural dye from purple cabbage (PCE) and green-synthesized the silver nanoparticle (AgNPs) from this extract for the light-harvesting material in DSSC. The anthocyanin was extracted with the maceration method for 24 hours with solvent variation (distilled water (DW), ethanol and methanol), followed by synthesized AgNPs. From FTIR, we found that the absorption area of anthocyanin at 1629 cm−1correspond with stretch vibration of C=O shifted to 1608 cm−1in AgNP, indicates the presence of amine group or flavanones group. The PCEs showed an amorphous non-Bragg diffraction peak at a range of (15-25)°. AgNP’s diffractogram showed an intense peak at around 37.94° originates from Ag. Visible light range absorption observed, peaked at (421, 480, 550, and 966) nm, (415 and 544) nm, and (409 and 544) for PCEs in DW, ethanol, and methanol, respectively. The peak at 550 nm that comes from aglycone group in anthocyanin would be disappeared in the AgNPs that was made by dissolving AgNO3in DW, ethanol, and methanol. The energy gap was (2.37, 3.00, and 3.03) eV for PCEs in DW, ethanol, and methanol, respectively, and (3.20, 3.30, and 3.31) eV for AgNPs. The reduction current originated from the Faradaic process (dark and irradiated condition) was detected in the extract with DW and ethanol as solvent, while it was not noticeable in methanol. This reduction current was detected for all solvents in AgNP positioned at a positive voltage of 0.2V. To be used as a light absorber in DSSC, one must choose the dye solution with the smallest energy gap without or small reduction current.
The improvement design of two-colour pyrometry for pulsed laser deposition system
Authors: Liang T. , Ningsih K. , Mackenzie J. I. , Prentice J. , Yasin M.
Published: June 2022

In this work, we develop a digital pyrometry with an automatic control system. A two-colour pyrometer is applied to measure the substrate surface temperature in the pulsed laser dep-osition (PLD) system. A digital computer and two-colour photodetector are coupled to obtain the substrate surface temperature and the output signal from the respective detectors with high accuracy. These sets enable us to determine the substrate temperature during the process of deposition remotely and potentially allow us to develop control routines for maintaining a constant temperature throughout the process. The designed system has a broad spectral response range from 0.32 to 1.7μm and achieves a deficient full-scale temperature error of <1.8°C. Factors affecting the temperature measurements are studied to identify the sensor limitations, such as possible damage on the two-colour photodetectors, spectral losses, responsivity, and the distance between the photodetector end to the substrate. Finally, this pyrometric system is applied in the PLD process to maintain a stable substrate surface temperature.
Refractive index sensing performance of a bimetallic core-shell nanotube
Authors: Azwar Azrul
Published: June 2022

The sensing performance of a bimetallic core-shell nanotube is studied theoretically based on the theory of TE-polarized light scattering by a multilayer infinite cylinder. The nanotube consists of a metallic core and a metallic shell with the analyte is inserted between the core and the shell. It is found that the absorption efficiency spectra of a bimetallic core-shell nanotube exhibit three resonance peaks correspond to the dipole, quadrupole and sextupole mode. As the refractive index of the analyte increased from n2
= 1.33 to n2
= 1.45, these resonance peaks are linearly redshifted. By calculating the figure of merit (FOM), it is found that the high sensing performance with FOM > 100 could be achieved. The dipole mode exhibits a higher sensing performance as compared to the other modes. Finally, the sensing performance is very sensitive to variations of the geometrical parameter and the background medium of the nanotube.
Application of ipv6 technology based on improved ant colony algorithm in digital twin watershed
Authors: Lingming Meng , Fei Peng , Peng Zhang , Shuang Jiang , Yun Chen
Published: June 2022

With the Internet of Things, the rapid development of the Internet and the rising number of online users, IPv4 addresses used today have been allocated, and IP addresses have become scarce, unable to meet the growing demand for IP addresses. This paper provides a basic theory of big data analysis and research on social relationships and sense of location information based on the relevant information of a model and functions of the business processing layer, transmission layer, information processing and application layer extracted from the network and social material basis. The results show that this method has better fitting and prediction effect by using ipv6 technology of ant colony algorithm. It lays a foundation for further research in the future. It can be seen from the experimental results that the performance of the algorithm decreases obviously with the increase of feature proportion. This is because the increase of feature proportion makes the algorithm select redundant and irrelevant features, resulting in the decline of classification accuracy. The results show that the accuracy of eACO-GA algorithm is 0.98 to determine the optimal feature selection ratio of the current data set, and better classification results can be obtained.
The influence of wind turbine blade rotation on anemometer
Authors: Zhou Yaqiang , Tian Lizhu , Jiang Zhiwen , Li Yapeng , Wu Zhaohe , Qi Chenglong , Gou Yanxu , Xu Yonghe , Du Dayu , Wang Bao , Wu Yuan , Feng Wei , Li Peng
Published: June 2022

In this thesis, numerical simulation modeling is used to calculate the influence of wake on the wind speed anemometer. The input conditions include wind speed, wind direction, wind density, etc., and a matrix database is formed, which is used to call data with lidar. Evaluation of the actual deviation of wind speed and direction at different wind speeds. Evaluation of the actual deviation of the anemometer under different installation positions. Through the results of numerical analysis, improve the wind speed and direction collection accuracy of the unit.
Design of Ducted Fan Based on Optimal Circulation Distribution
Authors: Zhang Zilun , Bao Mingmin , Qiao Nanxuan , Ma Tielin
Published: June 2022

The ducted fan lift system has been widely used in vertical takeoff and landing (VTOL) unmanned aerial vehicle (UAV). According to the overall design requirements of a VTOL UAV, based on the optimal circulation distribution condition without blade element drag and combined with strip theory, the blade torsion angle distribution and chord length distribution are given. The parameters of ducted fan are designed, and the preliminary design of ducted fan lift system of this UAV is completed. The aerodynamic characteristics of the isolated fan and the ducted fan are compared by numerical simulation method, and the thrust characteristics of the ducted fan at different flight speeds are calculated. The results show that the duct increases the induced velocity at the propeller. Compared with the isolated fan, the power load and hover efficiency of the ducted fan are increased by 36.8% and 36.3% respectively. The hovering efficiency of the ducted fan designed by this method reaches 83%, which meets the design requirements and proves the effectiveness of the design method.
Numerical investigation of the aerodynamic interference in 2-aircraft formation flight
Authors: Cui Xingda , Yu Yonggang , Ma Shuai , Xiao Zhongyun , Zhang Lu , Liu Fang
Published: June 2022

Due to obvious reduction in drag, formation flight attracts wide attention of major powers in the world. Based on wild geese flying in a ‘V’ formation, a formation composed of two flying-wing aircrafts is designed. The aerodynamic interference in 2-aircraft formation flight is studied by CFD. Results show that 2-aircraft formation flight has little impact on leading aircraft, but has an evident impact on following aircraft. At the same AoA, the effect of increment in lift and reduction in drag of following aircraft is large. As considering the balance of gravity and lift, the reduction in drag of following aircraft is much larger, that is up to 25.1%. Under the aerodynamic interference effect, the following aircraft has a nosedown pitching moment increment, and becomes lateral static instability, which is opposite to the characteristic of solo flying-wing aircraft. The aerodynamic interference mainly comes from upwash flow induced by wingtip vortex of leading aircraft, which reduces the actual AoA and induced drag of following aircraft, and changes the lift distribution of both sides of following aircraft.
Research on dust suppression technology of fully mechanized mining workers by section control of airflow
Authors: Chen Fang
Published: June 2022

Taking the 20106 fully mechanized mining face of Wangjialing coal mine as the engineering background, this paper analyzes the action relationship between the dusty air flow and fresh air flow formed by the coal caving and dust production of the fully mechanized mining machine, and through the establishment of mathematical model and field test, the best matching parameters of the relative position between the axial and radial air outlet of the segmented air control and dust control system and the head-on of the working face are obtained. The field application shows that after the optimization of the parameters of the wind and dust control system, the dust reduction efficiency of the total dust concentration at the driver’s position and each transfer point can be increased by about 80%, and the dust reduction efficiency at the driver’s position can reach 91.8%. The high concentration dust is controlled within 2m in front of the work, which can prevent the escape and diffusion of dust to the rear, and the working environment is significantly improved.
The experimental study of converging slot-holes (consoles) with different transition surfaces
Authors: Huang Ying , Wang Hao , Peng Can , Zhang Jingzhou
Published: June 2022

In order to study the effect of consoles with different transition surfaces on film cooling performance, four kinds of consoles with different transition surfaces were designed. Under the same boundary conditions, a series of experimental studies were carried out under two typical blowing ratios. The experimental results show that whether under M=0.5 or M=1.5, compared with the reference case, the console with anti-S-shaped transition surface has the best spatially-averaged adiabatic film cooling effectiveness (ηad,av
), and the ηad,av
is improved by 7.6% and 6.6% respectively. Meanwhile, the discharge coefficient (Cd
) is decreased by 2.6% and 2.2% respectively.
Causes and troubleshooting of high bearing bush temperature of a nuclear power steam turbine
Authors: Li Shuaishuai , Qu Tianzuo
Published: June 2022

As an important part of the steam turbine unit, once the temperature of the bearing bush rises abnormally, it will not only reduce the application performance of the bearing itself, but also affect the normal operation of the whole unit, resulting in shutdown accidents. Aiming at the problem of abnormal temperature rise of bearing bush of nuclear power steam turbine, combined with the operation and maintenance of the unit, the real cause of high bearing bush temperature is clarified, and then targeted treatment measures are taken to solve the problem, which is beneficial to ensure the safety of the unit.
Comparative experimental study on dynamic characteristics of bubble microlayers in small channel flow boiling and pool boiling
Authors: Shen Zhongxiang , Gao Ming , Dong Wuhan , Zhang Lixin
Published: June 2022

The microlayer present at the bottom of the bubble plays a very important role in heat transfer during nucleation boiling. In this paper, the dynamic characteristics of microlayer at the bottom of boiling bubble in a small channel were studied by laser interferometry method and high speed camera, and the results were compared with pool boiling experiments. The results show that the bubbles have an obvious tendency to slip in the flow boiling. The microlayer interference fringe is deformed and no longer a complete Newtonian ring. By analyzing the thickness distribution of microlayer in different directions in flow boiling and the change of micro-contact angle in the flow direction, it was found that the micro-contact angle in the flow direction became larger with the growth of bubbles.
Design and analysis of a new heavy oil pump based on CFD
Authors: Sun Yi , Meng Fanxiang , Pan Lichao , Wang Xu
Published: June 2022

At present, submersible electric pump is the main oil production equipment in the world’s oil fields. Because the pump is tested with clean water as the medium when it leaves the factory, it can not be widely used in all oil fields. In this paper, a prototype submersible electric pump is improved and designed according to the actual working conditions, and a new heavy oil pump is obtained, which can be widely used in heavy oil Wells. The static pressure distribution and velocity vector distribution under the actual working conditions were simulated by CFD, and the feasibility was verified. It provides theoretical basis and technical guidance for solving the adverse effect of high viscosity produced liquid on pump, and has certain guiding significance for oilfield pump selection. So as to effectively save electricity and rationally exploit energy.
Optimization of Dual Unloading Grooved Piston Pump Distributor Based on Penalty Function Method
Authors: Song Yuning , Han Liang
Published: June 2022

According to the problem of noise caused by fluid pulsation in the piston pump, and related to the opening form, position and size of damping slot on the flow plate, a new type of distribution disc with double V discharge slot is designed again. Then CFD simulation software is used to simulate the design of the flow distribution disc into the piston pump. Finally, through simulation, it is concluded that the width of the triangle slot of the distribution plate is about 10°, the slope angle is about 12°, and the diameter of the unloading hole is about 0.8mm. When the diameter of the hole in the unloading hole is about 1.5mm, the flow curve is the smoother, and the pressure is the smoothest. Force shock and noise are also minimized at this time.
A new unstructured hybrid mesh generation method based on BP-ANN
Authors: Lu Peng , Wang Nianhua , Lin Yi , Zhang Xiaorong , Wu Yadong , Zhang Hongying
Published: June 2022

The automation and intelligence of grid generation are still bottleneck problems in computational fluid dynamics. This problem can be solved by generating anisotropic quadrilateral by advancing layer method and isotropic triangular mesh by advancing front method. However, the advancing layer method needs to calculate the advancing direction, step size, a correction factor of the concave and convex area, so the automation level and efficiency of grid generation need to be improved. To solve the above problems, a hybrid grid generation method based on BP-ANN is proposed. The grid data generated by traditional methods are learned by a neural network, and the neural network can predict the above key parameters. Finally, a mesh generation example of 30P30N multi-element airfoil shows that the proposed algorithm can effectively improve the adaptability, efficiency and quality of hybrid mesh generation.
Research on Influence Factors of Fluid-induced Force in labyrinth liquid Seals for pump
Authors: Chen Pingwei , Wang Tong , Ma Wensheng , Wang Tianzhou , Cao Rui
Published: June 2022

A 3D model of straight-through labyrinth liquid seal for water pump was built to analyse the fluid-induced forces. We found that the eccentricity and pressure difference have great impact on both the tangential force and the radial force. The tangential force increases along with the rotating speed. When tooth hight is Th=2.4mm, the tangential force comes to the minimum. When tooth width Tw =2.0mm, the radial force comes to the maximum. The tooth numbers have a great influence on the fluid-induced force. The more number of sealing teeth will cause the instability the sea.
Dynamic Simulation Analysis of Aircraft Hydraulic Pipeline System under Different Pressure
Authors: Liao Zhenhua , Zhai Guangjie , Tang Jie
Published: June 2022

The hydraulic system is very important in the aircraft structural system, but the hydraulic pipeline is prone to cracks or even breaks due to vibration problems during system operation, causing major hidden dangers to flight safety. Using ANSYS Workbench to carry out modal analysis and harmonic response analysis of pipelines, the influence of different inlet pressures on pipeline vibration under pulsation excitation is compared and analyzed, which provides theoretical guidance for pipeline vibration research.
Numerical Simulation on Environmental Capacity Assessment in Sanmen Bay, China
Authors: Yao Yanming , Zhu Jiahao , Li Li , Wang Jiachen
Published: June 2022

Estuarine environmental capacity is the foundation for coastal biological diversity and self-purification capacity. Hence, studies on the marine environmental capacity (MEC) are the foundation for the total discharge control and water quality improvement of land-based pollutants. In the article, A calibrated two-dimensional hydrodynamic model was used to study the environmental characteristics of Sanmen Bay. The model results were used to estimate the environmental capacity of the bay. Taking the pollution problem in Sanmen Bay as an example, the method of response factor, the sub-unit control method, and the phased control method were used to estimate the environmental capacity, pollutant amounts, and the pollutant reduction in the bay. The concentrations of COD, inorganic nitrogen, and acid salt in Sanmen Bay are spatially varied, with higher values occurring in the western part and in the inner bay. The half exchange time of the whole bay is about 23 days, and the exchange time of 95% water body is about 60 days. The evaluation of MEC can not only provide technical support for the offshore aquaculture industries but also provide a scientific basis for the total control of terrigenous pollutants in coastal cities in Southern Zhejiang Province.
An analysis of the perturbation error bounds for singular and eigenvalues of diagonally dominant matrices
Authors: Li Jiangjiang , Liu Tianhua
Published: June 2022

In this paper, we investigate the error bounds of singular values and eigenvalues for diagonally dominant Hermite matrices when the matrix on its off-diagonal entries and on diagonally dominant part is perturbed with bound ε. Our results show that not only is the bound independent of the condition number of the matrix, but the matrix itself need not be symmetric positive definite. Furthermore, the bounds are applicable to both the eigenvalue and singular value of the matrix and can be used in generalized eigenvalue problems.
Study on eigenvalue and eigenvector introduction
Authors: Jiang Yinshan
Published: June 2022

The eigenvalue and eigenvector of matrix is one of the key contents of linear algebra, and it is also the hot topic of postgraduate entrance examination. First of all, we must understand the concept of eigenvalue and eigenvector and master the method of solving eigenvalue and eigenvector of matrix.
Convergence Analysis of EM Method in BSM Option Pricing Model
Authors: Cheng Qianmu , Yang Yuxi , Zhang Ling , Wu Delin
Published: June 2022

In this paper, the EM method is applied to the BSM option pricing model. The convergence of the numerical solution of the model is analyzed. Firstly, the application background and research significance of the model are given. Secondly, the convergence analysis of model and numerical solutions is presented. Finally,the consequences are connected to a viable illustration to confirm the results.
Explosion Yield Estimation of Multi-Ground-Medium-Mixed Site
Authors: Zhang Liangyong , Xiao Weiguo , Li Xin , Hu Xiaolin , Yin Wenjun , Li Pengyi , Tang Shiying
Published: June 2022

The seismo-acoustic analysis approach, which is based on the fusion of acoustic and seismic data, is an extremely effective way of monitoring the yield of explosions over a long distance. To address the problem of estimating the explosion yield at a multi-ground-medium-mixed site (abbreviated as mixed site), this article derives the general explosion yield prediction forms of acoustic model and seismic model, establishes the inversion method for explosion source parameters at mixed site by introducing the ground medium amplification factor, analyzes the inversion accuracy by using experimental data, and discusses the amplification effect and the influence of different scaling relationships. The experimental results indicate that the dispersion of the acoustic impulse relative to the overpressure decreases with distance and the linear relationship of acoustic impulse is better on a logarithmic scale, whereas the vertical component of the first peak of the seismic particle velocity and displacement, as well as the radial-vertical-tangent vector sum, exhibit a good linear variation law over a certain range on the logarithmic scale. The results of the source parameter inversion demonstrate that when the amplification factor is introduced, the inversion of the explosion source parameters of the mixed site has a high accuracy for yield estimation; however, when only single hard-rock media is considered, the inversion of the explosion source parameters produces large errors. The results of the amplification effect and scaling relationship analysis indicate that geological amplification has a substantial effect on the explosion source parameter inversion results, and that the data dispersion degrees of Sachs and KG85 scaling relationships are essentially identical.
Scale-free and small-world properties in an incompatibility hierarchical network
Authors: Wang Min. , Tian Da Ping.
Published: June 2022

In accordance with a particular iterative method, an incompatibility hierarchical network is introduced and the topological features of the network is investigated, It contains the degree distribution, diameter, clustering coefficient, second moment of distribution and degree correlations. The incompatibility hierarchical network is a simultaneous small-world, scale-free, assortative and divergent, which makes it possible to research the complexity of some real networks.
Simulation Analysis of Vibration Characteristics of the Submerged-propeller Shaft Coupling System
Authors: Tan Yuhang , Peng Weicai , Shen Lijiao , Xing Junhua
Published: June 2022

The vibration characteristics of the submerged-propeller shaft coupling system are studied in this paper. Firstly, Based on the fluid structure interaction theory on acoustics wave equation, the vibration analysis model of the propeller-shaft system under water is established and computed. And the vibration characteristics of coupling system is analysed by comparing the shaft system and the submerged-propeller system. The results show that the natural vibration of the coupling system presents complicated propeller-shaft strong or weak coupling characteristics. Comparing the natural vibration and frequencies of the shaft system and the submerged-propeller system, all of the coupling system modes are corresponding to the shaft system or the submerged-propeller system in low frequency range. And there is strong transverse coupled vibration of coupling system near the propeller’s 1st-order transverse vibration frequency, which appears as propeller’s 1st-order transverse vibration coupling shaft’s 2nd-order transverse vibration. That indicates the strong transverse coupled natural vibration of the coupling system is easy to be excited near the low order natural frequency of propeller. Which may cause propeller’s transverse excitation force to be easily transmitted to the hull through the bearings under non-uniform flow, resulting in the severe vibration of the hull stern.
Configuration Transformation Planning Method of Unmanned Aerial Vehicle Cluster Based on Improved Hungarian Algorithm
Authors: Shen XiaoDong , Chen Lei
Published: June 2022

For the planning problem of Unmanned Aerial Vehicle (UAV) formation configuration transformation, a formation configuration transformation planning method based on the improved Hungarian algorithm is proposed. By selecting a straight-line path as the movement path of UAVs in configuration transformation, the configuration transformation problem is transformed into a multi-UAV position assignment problem with constraint handling in a dynamic environment. For the Hungarian algorithm efficiency matrix power function treatment, the improved algorithm can be simultaneously bivariate integrated optimization; Introduce the time axis in the configuration space to establish the configuration-time space, and analyze the collision constraints during the dynamic transformation process in this space, and finally, the feasibility of the method is verified by simulation.
Abrupt changes detection using wavelet-based denoising analysis
Authors: Yang Chen , Zhu Li , Tian Xiangpeng , Xiao Yu , Li Qinghai , Liu Wei
Published: June 2022

Switching power supply is an essential power supply method that exists in the development of the electronic information industry. Drive power supply has various quality problems, primarily due to the loss of power inductors; for power inductor capacity testing, making a feasibility assessment is of great significance. In this study, we present a wavelet-based approach for detecting sudden changes in the power inductor current curve. To reliably identify rapid changes in the saturation of the inductor current after energization, the discrete wavelet transform is utilized to analyze the signal within a specified subset of all scaling and translation values, displaying different local signal characteristics.
Research on Rocket Telemetry Image Classification Based on CNN
Authors: Li Mingliang , Peng Yulu , Zhao Mei , Yang Xiaobo , Wang Sheng
Published: June 2022

The Rocket telemetry image is an important part of rocket flight data. At present, the Rocket telemetry image is still classified by manual. This method is inefficient and time-consuming. In this paper, the Rocket telemetry image is classified by using Convolutional Neural Network(CNN). Then the rocket flight stage is automatically determines by machine vision. These can set the foundation for future utilization.
Real-time density feedback control in ADITYA-U Tokamak
Authors: Patel K. , Nagora U.C. , Joshi H.C. , Pathak S.K. , Jadeja K.A. , Patel K.M. , Virani C. , Patel A. , Tanna R.L. , Kumar R. , Aich S. , Ghosh J.
Published: June 2022

A real-time density feedback control system with a 100 GHz
heterodyne interferometer has been designed, developed, and
commissioned in ADITYA-U tokamak. It consists of three subsystems
i.e. density measurement, feedback control, and gas fuelling. A
proportional feedback controller is configured in voltage amplitude
mode to operate the piezo valve for gas injection. Experiments are
performed during plasma discharges to achieve a predefined density
evolution as well as constant density. Stickiness of the piezo
valve restricts the temporal response of the valve. It is required
to minimize during the plasma discharge for a fast density response
which is achieved by a short preceding voltage pulse known as a
stick pulse. This paper describes the implementation of a real-time
density feedback control system which is successfully validated
using another existing 140 GHz interferometer system in ADITYA-U.
Moreover, the developed system consumes low power, is cost-effective
and re-programmable, can be easily upgraded, and provides interlock
with plasma parameters.
Energy transfer in a type-I van der Waals heterostructure of WSe2/PtSe2
Authors: Wang Pengzhi , Wang Yongsheng , Bian Ang , Hao Shengcai , Miao Qing , Zhang Xiaoxian , He Jiaqi , He Dawei , Zhao Hui
Published: June 2022

Energy transfer of a van der Waals heterostructure formed by monolayers of WSe2 and PtSe2 is studied by steady-state photoluminescence (PL) and time-resolved transient absorption spectroscopy. The heterostructure sample is fabricated by transferring a mechanically exfoliated WSe2 monolayer onto a PtSe2 monolayer film obtained by chemical vapor deposition. The sample is thermally annealed to improve the interface quality. PL of the heterostructure is quenched by four times compared to the individual WSe2 monolayer, indicating excitation transfer from WSe2 to PtSe2. Femtosecond transient absorption measurements with two configurations show that both the electrons and the holes can transfer from WSe2 to PtSe2 on a sub-picosecond time scale, while neither can transfer from PtSe2 to WSe2. These results indicate that WSe2 and PtSe2 monolayers form a type-I band alignment with both the conduction band minimum and the valence band maximum in the PtSe2 layer.
Two-dimensional polymers made of carbonyl-bridged heterotriangulenes are promising anode materials for Li-ion batteries
Authors: Yang Youchao , Geng Weixiang , Xu Tianze , Jing Yu
Published: June 2022

By means of first-principles calculations, we have explored the potential of two-dimensional (2D) polymers made of carbonyl-bridged triphenylamine (CTPA) and carbonyl-bridged triphenylborane (CTPB) as electrode materials for lithium-ion batteries (LIBs). Our investigations demonstrate that the carbonyl groups of 2D CTPB and CTPA are rather active to accommodate Li. Both 2D CTPA and CTPB show the transition from semiconductor to metal after combining with Li. The migration of Li through the pore space of 2D CTPB and CTPA is facilitated with a small diffusion barrier of 0.76 and 0.79 eV, respectively. 2D CTPB exhibits a high theoretical capacity of 760.86 mAh g−1 because it can accommodate Li at both the carbonyl sites and the surface sites of the skeleton, which is ascribed to the promotion of the electron-deficient B center. As a comparison, 2D CTPA can only combine with Li at the carbonyl sites and shows a capacity of 251.09 mAh g−1. With fast Li-diffusion ability, high capacity and low average operating voltage, 2D CTPA and CTPB are predicted to be promising non-metal anode materials for LIBs.
Templated synthesis of crystalline mesoporous CeO2 with organosilane-containing polymers: balancing porosity, crystallinity and catalytic activity
Authors: Luo Qiang , Wei Zichao , Duan Hanyi , Jin Lei , Kankanamage Rumasha N T , Shuster Seth , Suib Steven L , Rusling James F , He Jie
Published: June 2022

We report the synthesis of ordered mesoporous ceria (mCeO2) with highly crystallinity and thermal stability using hybrid polymer templates consisting of organosilanes. Those organosilane-containing polymers can convert into silica-like nanostructures that further serve as thermally stable and mechanically strong templates to prevent the collapse of mesoporous frameworks during thermal-induced crystallization. Using a simple evaporation-induced self-assembly process, control of the interaction between templates and metal precursors allows the co-self-assembly of polymer micelles and Ce3+ ions to form uniform porous structures. The porosity is well-retained after calcination up to 900 °C. After the thermal engineering at 700 °C for 12 h (mCeO2-700-12 h), mCeO2 still has a specific surface area of 96 m2 g−1 with a pore size of 14 nm. mCeO2 is demonstrated to be active for electrochemical oxidation of sulfite. mCeO2-700-12 h with a perfect balance of crystallinity and porosity shows the fastest intrinsic activity that is about 84 times more active than bulk CeO2 and 5 times more active than mCeO2 that has a lower crystallinity.
Evaluation of propensity score methods for causal inference with high-dimensional covariates
Authors: Gao Qian , Zhang Yu , Sun Hongwei , Wang Tong
Published: June 2022

In recent work, researchers have paid considerable attention to the estimation of causal effects in observational studies with a large number of covariates, which makes the unconfoundedness assumption plausible. In this paper, we review propensity score (PS) methods developed in high-dimensional settings and broadly group them into model-based methods that extend models for prediction to causal inference and balance-based methods that combine covariate balancing constraints. We conducted systematic simulation experiments to evaluate these two types of methods, and studied whether the use of balancing constraints further improved estimation performance. Our comparison methods were post-double-selection (PDS), double-index PS (DiPS), outcome-adaptive LASSO (OAL), group LASSO and doubly robust estimation (GLiDeR), high-dimensional covariate balancing PS (hdCBPS), regularized calibrated estimators (RCAL) and approximate residual balancing method (balanceHD). For the four model-based methods, simulation studies showed that GLiDeR was the most stable approach, with high estimation accuracy and precision, followed by PDS, OAL and DiPS. For balance-based methods, hdCBPS performed similarly to GLiDeR in terms of accuracy, and outperformed balanceHD and RCAL. These findings imply that PS methods do not benefit appreciably from covariate balancing constraints in high-dimensional settings. In conclusion, we recommend the preferential use of GLiDeR and hdCBPS approaches for estimating causal effects in high-dimensional settings; however, further studies on the construction of valid confidence intervals are required.
Analysis of Myocarditis Among 252 Million mRNA-1273 Recipients Worldwide
Authors: Straus Walter , Urdaneta Veronica , Esposito Daina B , Mansi James A , Sanz Rodriguez Cesar , Burton Paul , Vega José M
Published: June 2022

Background

Growing evidence indicates a causal relationship between SARS-CoV-2 infection and myocarditis. Post-authorization safety data have also identified myocarditis as a rare safety event following mRNA COVID-19 vaccination, particularly among adolescent and young-adult males after dose 2. We further evaluated the potential risk by querying the Moderna global safety database for myocarditis/myopericarditis reports among mRNA-1273 recipients worldwide.

Methods

Myocarditis/myopericarditis reports from 18 December 2020 to 15 February 2022 were reviewed and classified. The reported rate after any known mRNA-1273 dose was calculated according to age and sex, then compared with a population-based incidence rate to calculate observed-to-expected rate ratios (RRs).

Results

During the study period, 3017 myocarditis/myopericarditis cases among 252 million mRNA-1273 recipients who received at least 1 dose were reported to the Moderna global safety database. The overall reporting rate was 9.23 per 100 000 person-years, which was similar to the expected reference rate (9.0 cases per 100 000 person-years; RR [95% confidence interval (CI)], 1.03 [.97–1.08]). When stratified by sex and age, observed rates were highest for males aged <40 years, particularly those 18–24 years (53.76 per 100 000 person-years), which was higher than expected (RR [95% CI], 3.10 [2.68–3.58]). When considering only cases occurring within 7 days of a known dose, the observed rate was highest for males aged 18–24 years after dose 2 (4.23 per 100 000 doses administered).

Conclusions

Myocarditis/myopericarditis rates were not higher than expected for the overall population of mRNA-1273 recipients but were higher than expected in males aged 18–24 years, with most cases occurring 7 days after dose 2.