bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical research of lateral flow influence on supercavitating flow
Authors: Wang Min , Fan Chunyong , Hou Guisheng
Published: April 2022

In this paper, a recompiled multiphase flow solver, which introduced the lateral flow source into the code, is developed to investigate the effect of the lateral flow on the supercavitation phenomenon. The evolution of the supercavity profile and the resistance of the vehicle under different lateral flow speeds are studied. The results show that the recompiled solver can calculate the effect of the lateral flow on the supercavitation, and the influence of lateral flow on the supercavity is related to the speed of the counter flow. Under the same lateral flow velocity, the higher the convection velocity, the weaker the influence of lateral flow on the cavity profile and resistance. When the lateral flow velocity is less than 8% of the convection velocity, the effect of the lateral flow on the supercavity size and the resistance of the vehicle can be ignored. As the lateral flow strengthens, the supercavity will deform and even break and the resistance of the vehicle increases significantly. After removing the source of the lateral flow, the cavity re-grows again and forms a huge supercavity, which is much larger than the original one before introducing the velocity source. Then, the cavity gradually shrinks and reaches a new steady state.
Managing photoinduced electron transfer in AgInS2–CdS heterostructures
Authors: Kipkorir Anthony , Kamat Prashant V.
Published: April 2022

Ternary semiconductors such as AgInS2, with their interesting photocatalytic properties, can serve as building blocks to design light harvesting assemblies. The intraband transitions created by the metal ions extend the absorption well beyond the bandgap transition. The interfacial electron transfer of AgInS2 with surface bound ethyl viologen under bandgap and sub-bandgap irradiation as probed by steady state photolysis and transient absorption spectroscopy offers new insights into the participation of conduction band and trapped electrons. Capping AgInS2 with CdS shifts emission maximum to the blue and increases the emission yield as the surface defects are remediated. CdS capping also promotes charge separation as evident from the efficiency of electron transfer to ethyl viologen, which increased from 14% to 29%. The transient absorption measurements that elucidate the kinetic aspects of electron transfer processes in AgInS2 and CdS capped AgInS2 are presented. The improved performance of CdS capped AgInS2 offers new opportunities to employ them as photocatalysts.
Genetic parameters for milk yield, casein percentage, subclinical mastitis incidence and sexual precocity using Bayesian linear and threshold models
Authors: Colonia Saditt Rocio Robles , Oliveira Andréia do Carmo , Pilonetto Fabrício , Dauria Brayan Dias , Mourão Gerson Barreto , Machado Paulo Fernando , Nogueira Denismar Alves , Beijo Luiz Alberto , Petrini Juliana
Published: April 2022

Context The economic efficiency of a dairy system is associated with the animal’s productive and reproductive abilities. Therefore, selection criteria should include milk production and quality traits as well as traits related to health and fertility. Since such phenotypes can present non-normal distributions, the use of threshold models is appropriate to study the genetic variation of such traits. Aim To estimate variance components for dairy production and functional traits in a Brazilian Holstein cattle population using linear and threshold models under a Bayesian approach. Methods Data comprised 64 657 test-day records for milk yield (MY, kg/day), casein percentage (CP, % of milk) and subclinical mastitis incidence (SCM), along with 4460 records for sexual precocity (PREC) from 5439 cows. Both SCM and PREC were defined as binary traits. Genetic analyses were based on linear (for MY and CP) and threshold (for SCM and PREC) models using Bayesian estimation. Non-informative and informative priors were considered for variance components, and these models were compared using the deviance information criterion (DIC) and the absolute difference between DIC (Δ). Key results Posterior means of heritability for MY, CP, SCM and PREC were 0.14, 0.39, 0.13 and 0.38 (based on non-informative priors) and 0.13, 0.27, 0.13 and 0.44 (considering informative priors), respectively. The model based on non-informative priors was better (lower DIC) for CP, whereas for PREC, the best model used informative priors. No differences between priors (Δ < 5) were observed for MY and SCM. Conclusions Threshold models were adequate for the analysis of non-normally distributed traits. The use of informative priors can be beneficial if specification is based on results from similar databases and models. Due to their high genetic variation, CP and PREC can be considered as selection criteria in animal breeding programs. In turn, accurate genetic evaluation for MY and SCM will depend on the pedigree and the information from genetically correlated traits. Implications Our study contributes to the understanding of the variation under important dairy production traits in a tropical Holstein population and provides information on the use of Bayesian threshold models as an appropriate method for the evaluation of non-normally distributed phenotypes.
Liveweight gain and metabolisable energy requirements of young entire male Australian Rangeland goats in response to supplementation
Authors: Leo-Penu C. L. O. , Beasley A. M. , Poppi D. P. , Norton B. W. , Eyre K. E. , McLennan S. R. , Quigley S. P.
Published: April 2022

Context High international demand for goat meat and high prices for goat in Australia have resulted in a transition from opportunistic harvesting to more managed production systems for Rangeland goats. There is limited information available to establish feeding strategies to maximise growth rates of Rangeland goats within these developing managed production systems. Aims The aim of these experiments was to determine the response to supplements and the metabolisable energy requirements for maintenance and liveweight gain of young entire male Rangeland goats. Methods Dose–response relationships to various supplements were established in two experiments with young entire male Rangeland goats. In Experiment 1, 54 goats were allocated to rolled-wheat grain, rolled-sorghum grain, or lucerne pellet supplements offered from 0 (control) to 24 g dry matter/kg liveweight.day. In Experiment 2, 24 goats were allocated to a commercial starch-based pellet offered from 0 (control) to ad libitum. In both experiments, goats were held in individual pens and offered their daily supplement allowances with ad libitum access to Mitchell grass hay and drinking water for 70 days. Key results Total intake (30 to 32 g dry matter/kg liveweight.day) increased in a linear fashion with an increasing intake of all supplements. Maximum intake of rolled-wheat, rolled-sorghum, lucerne pellets and the commercial starch-based pellet supplements ranged from 18 to 22 g dry matter/kg liveweight.day. Unsupplemented goats lost liveweight (−20 to −32 g/day), while supplemented goats gained liveweight (0 to 126 g/day) in a linear fashion with an increasing supplement and metabolisable energy intake for all supplements, with the highest response in goats supplemented with the commercial starch-based pellets. Estimated metabolisable energy requirements to maintain liveweight (372 kJ/kg liveweight0.75.day) and for liveweight gain (35 kJ/g) of the goats were the same in both experiments. Conclusion Liveweight gain increased in a linear fashion with metabolisable energy intake, with the maximum rates of liveweight gain occurring when starch-based supplement intake was approximately 20 g dry matter/kg liveweight.day. Implications Supplementation with starch-based rations will increase liveweight gain and decrease age at turn-off of young entire male Rangeland goats; however, the local availability and cost of these supplements need to be considered.
High levels of anoxygenic photosynthesis revealed by dual-frequency Fourier photoacoustics in
Authors: Lysenko Vladimir , Varduny Tatyana
Published: April 2022

In contrast to oxygenic photosynthesis, true anoxygenic photosynthesis is not associated with O2 evolution originated from water photolysis but still converts light energy to that of the phosphoanhydride bonds of ATP. In a narrow sense, anoxygenic photosynthesis is mainly known as to be related to the purple and green sulfur bacteria, but in a broad sense, it also occurs in the vascular plants. The portion of photosynthetic water photolysis that is compensated by the processes of O2 uptake (respiration, photorespiration, Mehler cycle, etc.) may be referred to as ‘quasi’ anoxygenic photosynthesis. Photoacoustic method allows for the separate detection of photolytic O2 at frequencies of measuring light about 20–40 Hz, whereas at 250–400 Hz, it detects the photochemical energy storage. We have developed a fast-Fourier transform photoacoustic method enabling measurements of both these signals simultaneously in one sample. This method allows to calculate oxygenic coefficients, which reflect the part of photochemically stored light energy that is used for the water photolysis. We show that the true anoxygenic photosynthesis in Ailanthus altissima Mill. leaves reached very high levels under low light, under moderate light at the beginning of the 1-h period, and at the end of the 40-min period under saturating light.
Multiproxy approach to track changes in the ecological condition of wetlands in the Gunbower Forest, a Ramsar site
Authors: Mall Neeraj , Gell Peter , Kattel Giri R. , Gadd Patricia , Zawadzki Atun
Published: April 2022

Gunbower Forest is bordered by the Murray River and Gunbower Creek and hosts several floodplain wetlands listed under the Ramsar Convention. Sediment cores were retrieved from three wetlands to trace changes to their ecological state over time. The basal sediments of the wetlands date back to the beginning of river regulation in the 1930s, suggesting that only after then were they inundated sufficiently often to allow for net sediment accumulation. The diatoms preserved in the lower levels of all cores suggest clear, freshwater conditions prevailed during that period. Increased sediment and nutrient loads are inferred by increased epiphytic forms and nutrient indicators. Over recent decades the wetlands have transitioned to plankton dominance, reflecting greater connectivity to the river and distributary, and a reduced light environment. This pattern resembles to that recorded both upstream and downstream, suggesting a regional-scale change in the wetlands of the southern Murray–Darling Basin.
Atomically Dispersed Ni Single-Atoms Anchored on N-Doped Graphene Aerogels for Highly Efficient Electromagnetic Wave Absorption
Authors: Suo Bing , Zhang Xiao , Jiang Xinyu , Yan Feng , Luo Zhengzhi , Chen Yujin
Published: April 2022

Uniformly dispersed nickel single atoms (SAs) are experimentally prepared on ultralight N-doped graphene aerogels (Ni-SA@NRGA). The experimental results show that Ni-SAs in graphene aerogels can improve the conduction, polarization losses, and impedance matching properties of the Ni-SA@NRGA. As a result, the minimum reflection loss (R
L,min) of Ni-SA@NRGA is –49.46 dB with a matching thickness of 2.0 mm and the broadest efficient absorption bandwidth is 3.12 GHz at a low thickness of 1.5 mm. Meanwhile, even with a matching thickness of 1.2–2.0 mm, the R
L,min value of Ni-SA@NRGA can reach –20 dB. The current study demonstrates the significance of incorporating metal single atoms into graphene aerogel for electromagnetic wave absorption.
The Penrose property with a cosmological constant
Authors: Cameron Peter
Published: April 2022

A spacetime satisfies the non-timelike boundary version of the Penrose property if the timelike future of any point on

I

−

contains the whole of

I

+

. This property was first discussed for asymptotically flat spacetimes by Penrose, along with an equivalent definition (the finite version). In this paper we consider the Penrose property in greater generality. In particular we consider spacetimes with a non-zero cosmological constant and we note that the two versions of the property are no longer equivalent. In asymptotically AdS spacetimes it is necessary to re-state the property in a way which is more suited to spacetimes with a timelike boundary. We arrive at a property previously considered by Gao and Wald. Curiously, this property was shown to fail in spacetimes which focus null geodesics. This is in contrast to our findings in asymptotically flat and asymptotically de Sitter spacetimes. We then move on to consider some further example spacetimes (with zero cosmological constant) which highlight features of the Penrose property not previously considered. We discuss spacetimes which are the product of a Lorentzian and a compact Riemannian manifold. Perhaps surprisingly, we find that both versions of the Penrose property are satisfied in this product spacetime if and only if they are satisfied in the Lorentzian spacetime only. We also discuss the Ellis–Bronnikov wormhole (an example of a spacetime with more than one asymptotically flat end) and the Hayward metric (an example of a non-singular black hole spacetime).
Controlling degeneracy and magnetization switching in an artificial spin ice system of peanut-shaped nanomagnets
Authors: Chaurasiya Avinash , Anand Manish , Rawat Rajdeep Singh
Published: April 2022

Using extensive numerical simulations, we probe the magnetization switching in a two-dimensional artificial spin ice (ASI) system consisting of peanut-shaped nanomagnets. We also investigated the effect of external magnetic field on the degeneracy of the magnetic states in such a system. The switching field is found to be one order smaller in the proposed ASI system with peanut-shaped nanomagnets as compared to the conventionally used highly-anisotropic nanoisland such as elliptically shaped nanomagnets. The metastable two-in/two-out (Type II) magnetic state is robust at the remanence. We are also able to access the other possible microstate corresponding to Type II magnetic configurations by carefully varying the external magnetic field. It implies that one can control the degeneracy of the magnetic state by an application of suitable magnetic field. Interestingly, the magnetic charge neutrality at the vertex breaks due to the defects induced by removing nanomagnets. In such a case, the system also appears to have one-out/three-in or three-out/one-in (Type III) spin state, reminiscent of magnetic monopole at the vertex. We believe that our study is highly desirable in the context of developing the next-generation spintronics-based devices for future technologies.
Temperature-dependent enthalpy and entropy stabilization of solid solution phases in non-equiatomic CoCrFeNiTi high entropy alloys: computational phase diagrams and thermodynamics
Authors: Anis Geraldine , Attallah Moataz M , Youssef Mostafa , Salem Hanadi
Published: April 2022

Research interest in multi-principal element high entropy alloys (HEAs) has increased drastically since the field was first formally introduced in 2004. Since then, HEAs have become important candidate materials for many key applications. However, despite the progress made in this field, there remains much ambiguity surrounding HEA phase stabilities. To that end, the calculation of phase diagrams (CALPHAD) method was used to construct extensive temperature-composition phase diagrams of the CoCrFeNi
x
Ti2−x
, Co
x
CrFeNiTi2−x
, CoCrFe
x
NiTi2−x
, and CoCr
x
FeNiTi2−x
HEA systems. Due to its potentially favorable properties, the current work was focused on the single face-centered cubic (fcc) solid solution phase and an extensive thermodynamic analysis was carried out to examine the underlying thermodynamic factors of its stabilization. The mixing enthalpies and entropies of the alloys in the studied systems were calculated, where it was found that the single fcc solid solution phase can be either enthalpy- or entropy-stabilized depending on the temperature. The deviation of these quantities from the ideal solid solution thermodynamic behavior was considered, and it was found that close to and within the single fcc solid solution regions, the deviation is smallest in all systems. Furthermore, a preliminary exploration of the impact of interstitial nonmetals such as C, N, and O showed noticeable alteration of the phase equilibria of the studied systems. This work emphasizes the importance of exploring non-equiatomic compositions of HEAs as well as the necessity of a comprehensive thermodynamic analysis to understand HEAs phase stabilities.
Influence of oxygen vacancy defects on Aurivillius phase layered perovskite oxides of bismuth towards photocatalytic environmental remediation
Authors: Sharma Manisha , Kumar Ashish , Krishnan Venkata
Published: April 2022

The low light absorption and rapid recombination of photogenerated charge carriers are primary contributors to the low activity of various photocatalysts. Fabrication of oxygen vacancy defect-rich materials for improved photocatalytic activities has been attracting tremendous attention from researchers all over the world. In this work, we have compared the photocatalytic activities of oxygen vacancy-rich Bi2MoO6 (BMO-OV) and Bi2WO6 (BWO-OV) for the degradation of a model pharmaceutical pollutant, ciprofloxacin under visible light irradiation. The photocatalytic activity was increased from 47% to 77% and 40% to–67% for BMO-OV and BWO-OV, respectively in comparison to pristine oxides. This enhancement can be ascribed to suppressed charge carrier recombination and increased surface active sites. In addition, scavenger studies have been done to explain the role of photoinduced charge carriers in the degradation mechanism. Moreover, oxygen vacancy-rich photocatalysts have remained stable even after three consecutive cycles, making them promising materials for practical applications. Overall, this work provides deeper insight into the design and development of oxygen vacancy-rich materials.
Optimization and Fabrication of MEMS suspended structures for nanoscale thermoelectric devices
Authors: Wei Lei , Wei Jiangtao , Kuai Xuebao , You Zhiwei , Zhang Mingliang , Liu Wen , Yang Fuhua , Wang Xiaodong
Published: April 2022

By eliminating the influence of the substrate on parasitic thermal resistance, MEMS suspended structures become one of the accurate nanoscale thermoelectric performance evaluation devices. However, the process of MEMS suspended thermoelectric devices is complex, and its multilayer suspended structure is easy to fracture due to large stress. As a result, optimizing the design of suspended structures is critical in order to reduce manufacturing complexity and increase yield. In this study, finite element simulation is used to investigate the impacts of varying structures and sizes on the stress of MEMS suspended devices. The maximum stress and average stress of silicon nanomaterials are lowered by 90.89% and 92.35%, respectively, by optimizing the structure and size of the beams and nanobelt. Moreover, MEMS suspended devices of various structures are successfully manufactured. It not only increases the yield to more than 70% but also decreases the impact of strain on thermoelectric performance and can be used to create suspended devices with integrated silicon microstrips.
‘Levitation’ of a falling pencil
Authors: Cross Rod
Published: April 2022

If a pencil is held upright on a smooth horizontal surface and allowed to fall, then the bottom end first slides backward and then forward across the surface. If the top end of the pencil is given a firm horizontal push then the bottom end lifts off the surface and the whole pencil becomes airborne.
Mercury transit observed in Ghana
Authors: Proven-Adzri E , Ansah-Narh T , Aworka R , Fosuhene S K , Sottie S O , Gyasi G
Published: April 2022

The planet Mercury transited the face of the Sun in a rare spectacle on 11 November 2019. It was an awe-inspiring moment for 300 students from Kwabenya Community High School and Ghana Atomic Energy Commission Basic School in Ghana to see this wonder of the cosmos. Celestron Power Seeker 60 mm diameter telescopes were used to project the Sun’s image on a white card on the ground to observe safely. It was a time for the kids to relate the theory of eclipse and transits to a practical life experience. This was an avenue to introduce astronomy to the kids.
Interactions among school teachers, students and university researchers in workplace experiences using disused instruments of school laboratories
Authors: Riccardi P , Romano V , Pellegrino F
Published: April 2022

This work documents the collaboration between the Physics department of the University of Calabria and some schools of the region in a project devoted to recovering disused instrumentation in school laboratories. The project has been conceived as a workplace experience for the students, i.e. a learning experience in a real work place. In Italy, workplace experiences are mandatory for all students in the last 3 years (16–19 years old) of secondary education. The integration of these informal activities into the formal school context can allow structural and sustained connections between schools and research environments. In the following we describe how this integration has been implemented through a peer-to-peer interaction among school students, teachers and university researchers. The project, which entailed also the participation of the students in exhibits and public events, emphasizes the experimental activities in the physics laboratory as an important moment of aggregation and socialization.
A mnemonic device determining the vector direction in cross product transformations
Authors: Zhu Emily Y
Published: April 2022

Vector cross product transformations are essential components in general physics. The numerous mnemonic devices catered towards each potential transformation result in confusion, defeating their purpose of reducing learning barriers. Therefore, a general mnemonic device, subject–environment interaction or the subject, is proposed to help students in determining the resulting vector direction of various vector cross products.
Making jets of air visible in the infrared
Authors: Oss Stefano
Published: April 2022

An easy experiment is suggested to visualize the shape of a jet of hot air, coming from a hair dryer, which encounters obstacles along its path. Quite simply, owing to the heating produced on a flat surface, it is possible to acquire infrared thermal images of the jet. As a particular example, we observe the entrainment of air which is the basis of the Coanda effect.
Newton’s law of cooling with a low-cost thermoscope: physics in the time of covid-19
Authors: Bastos Rodrigo Oliveira , Cordeiro Filho Luiz Artur , Akio Ikeoka Renato
Published: April 2022

The necessity to teach experimental physics in the pandemic period motivated the development of practices in which students may take measurements with instruments constructed by themselves. In this article, we present an experimental practice to approach Newton’s law of cooling with a thermoscope (the earliest device for detecting changes in temperature, forerunner of the thermometer) constructed with household materials. Although the use of a non-calibrated thermoscope, the instrument presented several advantages, visual appeal, ease of handling, ease of data acquisition and good reproducibility. The students can take data, plot graphs, and verify if the Newton’s law of cooling holds on the tested circumstances.
A SiC sidewall enhanced trench JBS diode with improved forward performance
Authors: Kong Moufu , Chen Zongqi , Gao Jiacheng , Duan Yuanmiao , Hu Zewei , Yi Bo , Yang Hongqiang
Published: April 2022

A new high-performance sidewall enhanced trench junction barrier Schottky (SET-JBS) diode is proposed in this article. In the proposed SET-JBS diode, in addition to the Schottky contact on the top anode, the sidewall of the trenches also introduces Schottky contacts, which not only increases the Schottky contact area, but also weakens the junction field-effect transistor effect of the device, resulting in a high forward current density and a low specific on-resistance (R
on,sp) with a small increase in reverse leakage current (J
L). Simulation results show that the R
on,sp of the proposed SET-JBS diode is reduced by 21.6%–46.7% with less than an order of magnitude increase in leakage current compared with that of the conventional trench JBS (T-JBS) diode when the trench distance is from 2.1 μm to 1.2 μm at the 2 μm trench depth. And the SET-JBS diode also performs better than the trench MOS barrier Schottky (TMBS) diode when comprehensively considered the R
on,sp and J
L. And the figure of merit and the trade-off relationship between the R
on,sp and the breakdown voltage of the proposed SET-JBS both are better than those of the conventional T-JBS diode and TMBS diode. The forward I–V analytical model of the SET-JBS is also proposed, which is in good agreement with the simulation results. All the simulation results indicate that the proposed SET-JBS diode has promising potential in power electronics applications.
Multi-sensor target allocation model based on NC-PSO
Authors: Zhang Zhen , Wu Jianfeng , Xie Jiahao
Published: April 2022

Traditional multi-sensor target allocation often has problems such as slow algorithm iteration and low solution quality. In response to this problem, this paper proposes the NC-PSO algorithm, so that the particles can jump out of the local optimum and increase the convergence speed. At the same time, on the basis of the improved algorithm, the constraint of the target threat degree is added, the interval analytic hierarchy process is used to estimate the target threat, and the allocation principle is optimized, so that the use of sensor resources is better and the allocation is more reasonable. The simulation results prove that NC-PSO can allocate targets to multiple sensors faster and better.
Flexible force-sensitive distributed pressure sensing system for soft connection of aircraft Cockpit Cover
Authors: Wang Pengfei , Lv Enming , Xie Jinbiao , Zhang Ping
Published: April 2022

With respect to the actual application of the edge bonding of transparent part of the fighter jet cockpit cover by soft connection, the flexible force-sensitive distributed pressure sensor system is developed, which covers the flexible force-sensitive sensor, calibration device, circuit and data analysis software. The pressure distribution during pressurizing of the edge bonding of multidimensional curved surface transparent parts is vividly showcased by 2D and 3D images. A number of people are assigned to carry out operation. Based on the pressure distribution map and data acquisition, it is determined that the existing bonding process has the serious decificiency of uneven pressure distributio that cannot be addressed, and there is huge potential for improvement.
Security Threat Analysis and Corresponding Countermeasures for HTS Communication System
Authors: Ma Yongchun , Yang Deyun , Zhang Depeng , Wu Hailin , Li ChaoRan , Du Qianqian
Published: April 2022

In recent years, satellite communication has been widely used in various fields. With the increase of the satellite communication business, the requirement for information security is stronger. System security plays a significant role in the HTS communication system. First, this article gives a brief description of the HTS communication system, introducing the composition and characteristics of the system. Then, the security threats to the HTS communication system are analysed in three aspects: physical security threats, operational security threats and data security threats. Finally, the corresponding countermeasures for security threats are put forward, which can enhance the overall security level of the HTS communication system.
Research And Design of Intelligent Home Potting System Technology By Wireless Sensor Networks
Authors: Liu Wenyi
Published: April 2022

People often put potted plants at home in life, but they neglect to cultivate them due to busy work and study, or the lack of expertise related to potted plant cultivation leads to rotten and withered plants. An Exynos 4412 development board with a Linux system and multiple information acquisition sensors is designed using time series for this life background. The system is an intelligent home potted plant system with a Linux-based Exynos 4412 development board and multiple information collection sensors, using a time-series prediction model, deep convolutional neural network model, message queue telemetry transmission protocol, cloud storage and other technologies. The system realizes automatic scientific irrigation, soil fertility monitoring, and pest and disease warning for potted plants, thus ensuring healthy and robust growth of potted plants, and has a broad market space.
Performance Optimization of Suppression Method for Platform Vibration Noise based on Vector Hydrophone
Authors: Hu Tian , Xu Yougen , Ye Chuyang
Published: April 2022

Objective: Aiming at the vibration control problem existing in the vector hydrophone under platform vibration and noise excitation, two methods, adaptive noise cancellation algorithm and vibration reduction design, are used to suppress vibration and noise. Methods: A simulation model of vibration and noise signals in the side area of the platform is established first, and the simulation model is simulated by adaptive noise cancellation method. Then noise reduction simulation is carried out by seismic mitigation and isolation method. Finally, the simulation results of the two methods are compared to check the effectiveness of the two noise suppression methods. Results: The results show that adaptive noise cancellation algorithm can effectively cancel the line spectra of platform vibration and noise, and the reduction of continuous spectra is about 10 dB; while the vibration reduction method can reduce the whole vibration and noise of the model, and the vibration and noise interference of the vector hydrophone is reduced by about 15 dB. Conclusion: The obtained results can serve as valuable reference for the performance optimization of suppression methos for vector hydrophones under platform’s vibration and noise excitation.
Failure Warning of Harmonic Reducer Based on Power Prediction
Authors: Li Bin , Qin Chengjin , Tao Jianfeng , Liu Chengliang
Published: April 2022

—Harmonic reducer is the core component of industrial robots. During its operation, the power signal is a key parameter that embodies the performance of the harmonic reducer. Therefore, accurate power prediction of the harmonic reducer has instructive significance for its failure warning and performance prediction. In this paper, a hybrid deep neural network (DCBNN) based on CNN and BiLSTM was proposed to process the condition monitoring data of the harmonic reducer and improve the prediction accuracy of power signal. First, the operating parameters were pre-processed and the data sets were divided. Then, the pre-processed data were input into DCBNN, and the spatial characteristics and bidirectional timing dependencies of the condition monitoring data are captured by CNN and BiLSTM. On this basis, the absolute value of the residual of the actual power and the predicted value is obtained according to the prediction result, and the residual curve is fitted by the distribution fitting method to obtain the alarm threshold of the harmonic reducer failure warning. Finally, 8 different data sets constructed using the experimental data of the harmonic reducer are used to verify the effectiveness and superiority of the proposed method. The test results on the complete data set show that the DCBNN model can complete effectively failure warning of the harmonic reducer.
Design and motion analysis of multi-motion mode pipeline robot
Authors: Yan Feng , Gao Haitao , Zhang Lei , Han Yali
Published: April 2022

Aiming to improve the adaptability level of single motion form pipeline robots, a wheeled pipeline robot with multiple motion modes is designed. The overall scheme of the pipeline robot is given. The self-adaptive diameter-changing mechanism, wheel displacement mechanism, and turning mechanism are designed. The motion and mechanical models of pipeline robots during travelling are established; on this basis, the robot‘s main body structure is optimised.
Control method of three-wheel intelligent tracking logistics car based on OpenMV4
Authors: Song Yuchen , xie zhijiang
Published: April 2022

The author designs an intelligent lifting transport device based on STM32 microcontroller. The lifting device is designed with STM32F407ZGT6 as the control core, and the hardware consists of OpenMV4 recognition, gray tracking, motor drive and other modules. It can carry out automatic, gray tracking, OpenMV4 recognition, intelligent material grasping and other functions, and can follow the track black line on the set plane track, and complete the preset operation. The experimental results are good.
Optimal Design of Machine Tool Vibration Reduction Based on Magneto-rheological Damper
Authors: Zhang Tieshan , Ren Zhong
Published: April 2022

This paper takes the three - way redundant drive parallel machine tool as research object, designs a magneto-rheological damper with displacement amplification function and simulates the magnetic circuit saturation of the damper by the Ansys workbench finite element analysis software, so that the output of the damper comes to optimization. The research results show that the magnetic field distribution is more reasonable, and the mechanical properties of the damper are improved. The optimization method is feasible and effective.
Vector control system design for asynchronous motors
Authors: Bai Panpan , Nie Wenyan
Published: April 2022

In order to decouple the excitation and torque components of the stator current so that the asynchronous motor speed control system approximates a DC speed control system. Firstly, the asynchronous motor model is transformed in coordinates, and then the vector control idea is proposed to construct a vector control system for the asynchronous motor. At the same time, a simulation model of the vector control system of an asynchronous motor was created on the Matlab platform and the speed waveform was recorded. The analysis of the experimental data showed that the speed response of the vector control system was fast and smooth, which improved the performance of the asynchronous motor speed control system.
Application of Edge Computing in the Quality Control of Cable Production Process
Authors: Xu Kan , Feng MingJun , Liu YuCheng , Deng HongGang
Published: April 2022

Given the lack of quantifiable evaluation criteria for the quality supervision and control in the existing power cable industry, insufficient research on the correlation of production indexes in the production process, and low timeliness in the analysis and processing of massive multi-source production data, the video monitoring model and data-driven process quality evaluation strategy model under the edge computing framework were constructed. Next, all the production data and test data in the cable production procedures were captured using edge nodes, and the factory-side data was cleansed, processed, and analyzed. The cable manufacturing quality was evaluated through edge computing, and the business process was arranged based on the edge computing results, so as to improve the cable product quality and finally optimize the total value chain of production in the whole cable industry.
Research on non-propellant electromagnetic controll based on Eddy Current Brake under non-uniform magnetic field
Authors: Liao Qian , Shi Yongkang
Published: April 2022

High-speed space debris threatens the safety of satellites in orbit, and efficient removal of space debris has become an inevitable trend. However, the spacecraft is still dependent on the active consumption of propellant to maintain the relative distance in the eddy current brake process. By discussing the high-speed rotating target of non-contact de-spun method and drawing technology, electromagnetic de-spun and drawing technology based on a non-uniform magnetic field is proposed to use alternating current form to control rotate-target magnetic field force during electromagnetic interaction process. Through the simplified model and condition, put forward electromagnetic satellite of one coil control method. The feasibility of the technique is verified by numerical simulation. The simulation results show that the relative distance between the electromagnetic satellite and the target can be effectively affected the output current of the electromagnetic coil controlled through distance feedback under nonuniform magnetic, so as to realize the long-term mission without propellant.
Influence of airfoil trailing edge on blade design and machining of small wind turbine
Authors: Lin Hanxiao , Sun Wenlei , Xing Xuefeng
Published: April 2022

In the design of small wind turbine, narrow structure is often produced at the trailing edge of airfoil, which brings great difficulties to production and processing. In this paper, the airfoil sd7080 is modified by removing part of the airfoil trailing edge to meet the processing technology. Through the calculation and analysis of the Q blade software, part of the airfoil trailing edge is removed, and the airfoil and wind-wheel aerodynamic characteristics are changed. Results: Under the same angle of attack, after removing part of the airfoil trailing edge, The lift coefficient CL and drag coefficient Cd of the airfoil are reduced, α<8.6°, the lift-to-drag ratio CL/Cd decreases, α>8.6°, the lift-to-drag ratio Cl/Cd slightly increases; After removing the trailing edge of some airfoils, the wind energy utilization coefficient CP, torque and thrust of the wind turbine are slightly reduced, and the aerodynamic performance meets the use requirements. Finally, this paper introduces the blade modeling method, and processes the blade through 3D printing technology. The research provides reference significance for the initial design and processing of small wind turbine blades.
Monitoring system based on wireless temperature measuring device
Authors: Wu Tianyi , Xu Xiangyi , Chen Lu , Tang Weijie
Published: April 2022

This paper analyzes the current common problems in substation temperature measurement, and the transformer temperature measurement system is designed. The system includes a temperature collection node, a temperature concentrator and a remote monitoring center, which can perfectly realize the functions of temperature collection, wireless transmission and online monitoring. Through the actual application of the software, it can be seen that the various modules are operating normally and have reached the design goals.
Kinematics modeling of redundant manipulator based on screw theory and Newton-Raphson method
Authors: Ge Dawei
Published: April 2022

In this paper, forward kinematics and inverse kinematicsis algorithms are proposed to solve the problem that the redundant manipulator has more freedom than the traditional manipulator and cannot directly solve the inverse kinematics analytical solution. Firstly, the forward kinematics model is established through the screw theory; secondly, Newton-Raphson method is used to solve the inverse kinematics of the manipulator. Finally, the algorithms of redundant manipulator are verified through an example simulated by Matlab Robotics toolbox. The results show that the kinematic algorithms are correct, which provides a good algorithm basis for subsequent dynamic control.
Research on Fingerprint Recognition Algorithm
Authors: Tan Linglong , Chen Huanyun , Yin Xiaoyao , Zheng Shiqi
Published: April 2022

Fingerprint characteristics will not change due to growth or aging, and are unique and suitable for the field of identification. The fingerprint image is scanned from left to right and from top to bottom in order to scan the points on the entire image, and then the points on the image are judged to achieve fingerprint feature point extraction. Then, the fingerprint image is preprocessed and feature extracted, and the center point of the fingerprint, the direction field of the fingerprint image and the coordinates of the feature point are obtained. The reference direction of the fingerprint is extracted. After the reference point and the reference direction of the fingerprint are determined, the characteristic information of the fingerprint is modified and the characteristic information is expressed in polar coordinates. The template and the feature information of the input image are sorted in the direction according to the direction of increasing polar angle, and the feature information is connected in series. If the matching degree of feature points is greater than the preset value, it is considered that the two fingerprints are matched successfully. It can be seen from the experimental results that the two fingerprint images are loaded, the feature point map and the smooth processing map are extracted after preprocessing, and the feature point matching degree is calculated. It can be judged that the two fingerprint images are from the same fingerprint.
Deep learning-based defect detection for hot-rolled strip steel
Authors: Si Binglong , Yasengjiang Musha , Wu Huawen
Published: April 2022

Defects in the strip’s surface can have an impact on the strip company’s product sales. As a result, it’s crucial to spot flaws on the strip steel’s surface. The Faster R-CNN network is structurally upgraded for the issue of strip steel surface defect detection by employing FPN for feature fusion in the feature extraction layer, RoI Align instead of RoI Pooling in the pooling layer, and Softer-NMS in the final prediction fully connected layer. In addition, for training, transfer learning is employed. The experimental findings demonstrate that the suggested technique mAP outperforms the original Faster R-CNN by 7.6%, and the detection time is fast enough for strip steel detection online.
Model-Based Safety Analysis of Movement Authority Scenario in TcCBTC system
Authors: Lin Junting , Min Xiaoqin , Chai Jinchuan
Published: April 2022

Train-centric communication based train control (TcCBTC) system contains a variety of uncertain factors in the operation process, and the generation scenario of movement authority is a real-time process. In order to judge the impact of uncertain factors on system safety, it is necessary to conduct formal modeling and analysis for this implementation process. Aiming at the modeling and analysis of the system in an uncertain environment, firstly, the implementation process of TcCBTC movement authority was analyzed, and the hazard source identification is carried out by combining the hazard and operability study (HAZOP) method. Secondly, the movement authority generation process is modeled based on the stochastic hybrid automata theory, and the statistical sample data are simulated in UPPAAL-SMC. Finally, the statistical model checking algorithm was used to analyze the model quantitatively. The results showed that the model could meet the functional attribute requirements of movement authority generation in TcCBTC system, and describe the uncertain environment in the process of system operation. SMC method could quickly verify the impact of uncertain factors on the system, and provide a certain theoretical basis for subsequent TcCBTC system development and relevant specifications.
Finite time stability analysis for T-S fuzzy positive systems and its application in pest control
Authors: Yang Tong , Cheng Yuyin , Zhu Baolong
Published: April 2022

This paper is considered with the finite time stability (FTS) for positive nonlinear systems. First, the fuzzy copositive Lyapunov function (FCLF) is established to reduce the conservatism of FTS conditions. Then, by using FCLF, a new FTS criteria of the studied systems is established. Since, the time-derivatives (TD) of membership functions are considered in the stability analysis, our results are less conservative. Besides, the obtained conditions are expressed via the linear programming technique, that can be verified effectively. Finally, the pest-predator system is used to reflect the effectiveness of the results.
The adsorption postures of water on CH3NH3PbI3 surfaces: a first-principles insight
Authors: Pu Wenhua , Yang Hui , Xiao Wei , Li Xiaowu , Wang Ligen
Published: April 2022

Inorganic organic perovskite solar cells (PSCs) are a kind of solar cells with rapid development in recent years, but their poor environmental stability, such as the water degradation behavior, hinders their commercialization. Here, we have thoroughly studied the adsorption postures of water on CH3NH3PbI3 surfaces. It is found that the adsorption energy of water molecules on perovskite surfaces is [-0.63, -0.59] eV, and with different initial postures, water molecules could eventually be adsorbed above Pb atom in a horizontal structure. The interaction between the perovskite surface and water molecules mainly comes from the electron exchange of Pb-O atoms. The weak interaction between H-I atoms makes the H atom approach the I atom, which could help maintain a horizontal structure of water molecules. The interactions between perovskite surfaces and water are well explained by our DFT calculations.
Research on Leakage and Diffusion characteristics of Liquid Hydrogen Based on Gaussian Diffusion Model
Authors: Shi Bangkai , Chen Yanwei , Hu Yang , Wang Yawen
Published: April 2022

In order to analyze the diffusion characteristics of the hydrogen cloud during a liquid hydrogen leakage accident, the Matlab calculation program of liquid hydrogen leakage and diffusion was compiled based on the Gaussian diffusion theory, and analyzed the influence of wind speed, pressure, leakage area and other factors on the size of the dangerous area after liquid hydrogen leakage.The calculation results show that: the wind speed accelerates the diffusion, and the higher the wind speed, the stronger the dilution effect on the hydrogen cloud, and the smaller the dangerous area formed; the increase of pressure and leakage port area will increase the leakage of liquid hydrogen, and as a result, the scope of the dangerous area is increased.
Operating performance analysis of cold and heat sources composite based on ground source heat exchanger and hot water exchange tanks
Authors: Miao Jingquan , Gao Yan , Liu Jingru , Cao Qing , Dou Huawei , Li Yanlei , Ji Fengjun , Zhang Tao , Li Yanteng
Published: April 2022

Aiming at the air-conditioning system of underground space engineering, it is proposed to use ground source heat exchanger and hot water exchange tanks in parallel as a composite cold and heat source, which can simultaneously achieve energy-saving requirements. In order to explore the operating heat transfer characteristics of the composite cold and heat source system, a mathematical model of buried pipes and hot water exchange tanks was established. The simulation analysis of the influencing factors such as inlet temperature and fluid flow rate shows that under the condition of small flow rate, increasing the fluid flow rate can significantly improve the buried pipe and the hot water tank and the heat exchange effect; the greater the temperature difference between the inside and outside of the pipe, the better the heat exchange effect of the heat exchanger, under the same flow rate, the heat transfer coefficient of the spiral coil is KDN15>KDN20>KDN25. According to three different load conditions, the flow ratio of the composite cold and heat source is optimized and analyzed. The results show that as long as the flow ratio is properly controlled, the composite cold and heat source can meet the cooling requirements of the air-conditioning system under different working conditions. There is an optimal flow ratio between the heat sources. The greater the ratio R of the extreme working condition load change value to the standard working condition load value, the smaller the value of the optimal flow ratio, and it is not affected by the loop flow rate and the inlet water temperature change.