bluuebunny/crossref_metadata_2025 huggingface dataset:
Rolling bearing fault diagnosis based on multi-scale weighted visibility graph and multi-channel graph convolution network
Authors: Zuo Dong , Tang Tang , Chen Ming
Published: July 2023

Current data-driven fault diagnosis methods are prone to overfitting and a decrease in accuracy when working with only a limited number of labeled samples. Additionally, existing graph neural network-based fault diagnosis methods often fail to comprehensively utilize both global and local features. To address these challenges, we propose a rolling bearing fault diagnosis method based on multi-scale weighted visibility graph and a multi-channel graph convolutional network (MCGCN). Our approach converts vibration signals into multiple weighted graphs from the perspective of geometric meaning and extracts local node feature information and global topology information of graphs using MCGCN. Experimental results demonstrate that our method achieves excellent performance under both sufficient and limited data conditions, providing a promising approach for real-world industrial bearing fault diagnosis.
Design and optimization of lightweight bending strain energy harvesters using irradiation cross-linked polypropylene ferroelectret
Authors: Holzmann H , Park Y J , Stoll G , Atzrodt H , Herold S
Published: July 2023

In this work, a concept for bending strain energy harvesting with lightweight ferroelectrets subject to metallic host structures is proposed. The energy harvester (EH) works with the ferroelectret irradiation cross-linked polypropylene (IXPP) and uses the piezoelectric δ
33-mode by transferring in-plane bending strain energy of a host structure to a compression of an IXPP stack. This is achieved with a simple and lightweight transmission made of structural steel. In this way, a high ratio of generated power per used EH mass can be achieved, being the main design goal of this paper. To demonstrate this, miniature EHs as unit cells for larger EH systems are investigated. The strain magnitude of the excitation in an aircraft wing of

4.5
⋅

10

−
5

m

m

−
1

at 1.5 Hz from previous work is partly taken into account for calculations. In an analytical modeling approach, the energy conversion abilities of the presented concept is compared to concepts using lead zirconate titanate ceramics to stress the usefulness in cases where strain energy is the prominent source of vibration energy. Further, an optimization algorithm is presented for a static and a dynamic case without a host structure and for a dynamic case with an aluminum host structure. The optimized power output and power output per total EH mass for the three cases is calculated to

1.52
μ

W

and

271
μ

W

k
g

−
1

, 0.7 mW and 80 mW kg−1 as well as

6.53
μ

W

(at 1 N excitation magnitude) and

10.8

m
W

k
g

−
1

(at 1 N excitation magnitude) respectively. Finally, experimental results for case three are presented to validate the model of the proposed and optimized EH topology up to 500 Hz. The results further show a good mechanical reproducibility of the measured transfer behavior and a fairly good reproducibility of the mechanical-electrical results due to deviations in material properties. A comparison of the model with the experimental results shows a good agreement. Therefore a linear ferroelectret model appears to be suitable to predict the system behavior in lower and higher frequency ranges as well as for high ferroelectret material strains. The optimized EH provides a comparably high ratio of power output per mass when added to a structure like an aircraft which is shown in a comparison to other research works. The performance in a real application can be further improved to 52 mW within a 1 m2 area using a clustering approach, discussed in the paper. Large deformations of lightweight structures like aircraft wings at low and high frequencies can thus be exploited to provide enough electrical power decentrally for low-power consumers.
Abnormally autofocusing vortex Swallowtail Gaussian vector beam with low spatial coherence
Authors: Shi Jingyi , Liang Zehong , Wu You , Wei Quanfeng , Shui Lingling , Deng Dongmei
Published: July 2023

The precondition for the application of light beams is the ability to devise light distribution with high precision. Controlling more dimensions for structured light fields is an effective method to improve the ability to devise light distribution. The Swallowtail beam, due to its rich regulatory parameters, provides the possibility to design a light field with a specific intensity distribution. Utilizing the Swallowtail beam as a foundation, we design its initial phase, polarization, and coherent structure, and propose a partially coherent azimuthally polarized circular vortex Swallowtail Gaussian beam (PCAPCVSGB) in our paper. This beam exhibits an abnormal self-focusing ability and forms an easily adjustable optical potential well at the focal plane, providing another effective tool for achieving optical manipulation. In addition, the PCAPCVSGB also shows an interesting vector property. It possesses a stable polarization singularity even with changes in coherence and topological charges, which exhibits a potential application value in optical communication.
Nondegenerate two-way edge channels of plasmons in networks
Authors: Sasaki Ken-ichi
Published: July 2023

An effective one-dimensional channel is formed at the periphery of a two-dimensional electron gas by electronic edge states. Robust edge states with suppressed dissipation arise from the Landau quantization in a strong magnetic field, and propagation through an edge channel formed by these states is one-way. In general, two-way edge channels rather than one-way ones have more advantages for applications and are the main topic of topological insulators. However, two-way edge channels of these are degenerate in their energies, which causes backscattering and dissipation. Here, we show that excited states in networks composed of capacitively coupled integer quantum Hall systems exhibit macroscopic two-way edge channels with different energies. Theoretical results are derived on the basis of two known effects; each system has plasmonic excitations known as edge magnetoplasmons, and the chirality of each system is diverted only locally by the capacitive interaction between nearest-neighbor systems. Because of the simplicity of the model, various extensions from regular networks to more complicated higher-dimensional networks are possible. The networks provide an ideal platform to test the functionality of plasmonic one-dimensional edge channels and suggest a dynamical model of fractional Quantum Hall systems.
Gaussian beam propagation in a Lorentz-violating vacuum in the presence of a semi-transparent mirror
Authors: Escobar C A , Martín-Ruiz A , Mondragón M , Jáuregui R
Published: July 2023

In this paper we study the propagation of structured optical scalar beams in a Lorentz-violating (LV) vacuum parametrized by a constant 4-vector u

μ
and in the presence of a semi-transparent mirror. The two bosonic degrees of freedom of the electromagnetic field can be described by a LV extension of the massless scalar field theory, whose LV part is characterized by the term (u · ∂ϕ)2. The mirror at a surface Σ is modelled by a delta-type potential in the Lagrange density for the LV scalar field, i.e. λ
δ(Σ)ϕ
2, where the parameter λ controls the degree of transparency of the mirror. Using Green’s function techniques, we investigate the propagation of a Gaussian beam in the presence of a mirror which is perpendicular to the propagation direction and for two particular choices of the background 4-vector: parallel and perpendicular to the propagation direction. To quantify the Lorentz-violating effects we introduce the fidelity as a measurement of the closeness of the propagated field distribution with respect to that in the conventional vacuum. In the absence of the mirror (λ = 0) the fidelity is found to be close to one, and hence LV effects are quite small. However in the presence of the mirror, there are regions where the fidelity drops to zero, thus implying that LV effects could be clearly differentiated from the propagation in vacuum. Within the paraxial approximation we determine analytically the LV effects upon the Rayleigh range, the radius of the beam, the Gouy phase and the radius of curvature of the wavefronts. We discuss possible scenarios where our results could apply, by using optically transparent multiferroic materials, which offer unprecedented opportunities to tailor structured beam propagation, as well as to simulate an LV vacuum.
PIC simulations of stable surface waves on a subcritical fast magnetosonic shock front
Authors: Dieckmann M E , Huete C , Cobos F , Bret A , Folini D , Eliasson B , Walder R
Published: July 2023

We study with particle-in-cell (PIC) simulations the stability of fast magnetosonic shocks. They expand across a collisionless plasma and an orthogonal magnetic field that is aligned with one of the directions resolved by the 2D simulations. The shock speed is 1.6 times the fast magnetosonic speed when it enters a layer with a reduced density of mobile ions, which decreases the shock speed by up to 15% in 1D simulations. In the 2D simulations, the density of mobile ions in the layer varies sinusoidally perpendicularly to the shock normal. We resolve one sine period. This variation only leads to small changes in the shock speed evidencing a restoring force that opposes a shock deformation. As the shock propagates through the layer, the ion density becomes increasingly spatially modulated along the shock front and the magnetic field bulges out where the mobile ion density is lowest. The perturbed shock eventually reaches a steady state. Once it leaves the layer, the perturbations of the ion density and magnetic field oscillate along its front at a frequency close to the lower-hybrid frequency; the shock is mediated by a standing wave composed of obliquely propagating lower-hybrid waves. We perform three 2D simulations with different box lengths along the shock front. The shock front oscillations are aperiodically damped in the smallest box with the fastest variation of the ion density, strongly damped in the intermediate one, and weakly damped in the largest box. The shock front oscillations perturb the magnetic field in a spatial interval that extends by several electron skin depths upstream and downstream of the shock front and could give rise to Whistler waves that propagate along the shock’s magnetic field overshoot. Similar waves were observed in hybrid and PIC simulations and by the MMS satellite mission.
Tuning of magnetic properties of Al-doped cobalt ferrite nanofiber prepared by electrospinning technique
Authors: Das Tupan , Noor Saima , Kumari Suman , Mallick Jyotirekha , Shukla Anant , Datta Subhadeep , Manglam Murli Kumar , Kar Manoranjan
Published: July 2023

The Al-doped cobalt ferrite (CoFe2-xAlxO4) nanofiber has been prepared by employing the electrospinning technique. All the nanofibers are characterized by the XRD technique. The Rietveld refinement of the XRD pattern reveals the spinel cubic structure with the Fd

3
¯

m space group. The TEM micrographs confirm the formation of nanofiber with a nearly uniform diameter of ∼137 ± 10 nm. The magnetic properties of all the nanofibers have been investigated by measuring the M-H hysteresis loops with the help of a Vibrating sample magnetometer (VSM). The M-H loops analysis demonstrates a reduction in the saturation magnetization, and coercivity from 106.88 emu g−1 to 40.01 emu g−1 and 0.897 kOe to 0.324 kOe, respectively, with the increase in Al concentration in the nanofibers. The ‘Law of Approach to Saturation’ technique has been employed to understand the magnetocrystalline anisotropy constant in the samples. The magnetocrystalline anisotropy constant (K
1) decreases with the increase in Al3+ substitution in place of Fe3+ in the spinel cobalt ferrite nanofibers. A squeezing effect on the M-H loop near M = 0 is observed and, it has been analyzed by a hysteresis loop width (∆H) versus magnetization (M) plot. The squeezing effect has been observed due to the exchange interaction phenomenon between the magnetic and non-magnetic atoms in the Al-doped cobalt ferrite nanofiber. The magnetic properties study demonstrates that Al-doped cobalt ferrite nanofiber exhibits soft magnetic nature.
National round robin test (RRT) for delamination strength testing YBCO HTS wires at room temperature (RT) and 77K
Authors: Liu Chuanguang , Shi Yunfan , Liu Cong , Tao Shu , Liu Fang , Chen Sikan , Xia Huineng , Zhou Jun , Zhang Xing-Yi
Published: July 2023

Second generation high temperature superconducting coated conductors (2G HTS CCs) have become indispensable wires for high-field superconducting magnets. The transverse mechanical delamination strength (MDS) is a key parameter due to the multilayer structure of CCs. Determination of the MDS value is thus significant. In this study, we report the MDS results of national round robin test (RRT) conducted in china by the institutions of Lanzhou University, Institute of Plasma Physic, and Shanghai Superconductor Technology Co., Ltd at room temperature (RT) and 77 K, respectively, for the determination of 2G HTS CCs (copper-stabilized) transverse MDS by a standardized procedure. Data at RT and 77 K all showed good consistency, with the relative standard uncertainty of 2.22% and 2.35%, respectively, illustrating the reliability of the established procedure, which can be used as a reference for engineering CC manufacturing and design of application magnets.
Improving the accuracy of a weighing scale by rigorously combining measurements
Authors: Boguslawski M , Mirbach B
Published: July 2023

In this paper, we investigate the question of how much measurement accuracy of additive quantities can be increased by the method of combined measurements. Therefore, we consider measurements of all possible combinations of n labeled masses and then estimate the individual weights of the n masses by a linear regression approach. We present experimental results which motivate comprehensive simulation campaigns. These simulations provide valid statistical statements and reliable forecasts of the experimental results. A profound analytical treatment, in turn, supports these simulation outcomes with excellent consistency. One important achievement therein is a general analytical expression for the accuracy that can be achieved by combined measurements. It turns out this method allows to estimate the weight of mass elements with an accuracy that potentially under-runs by orders of magnitude the resolution of the scale used. In a broader sense, our work wants to promote the method and give inspirations to applications in various metrological fields beyond high-precision mass determination.
Lyapunov exponents and phase transitions of Born-Infeld AdS black holes
Authors: Yang Shaojie , Tao Jun , Mu Benrong , He Aoyun
Published: July 2023

In this paper, we characterize the phase transitons of Born-Infeld AdS black holes in terms of Lyapunov exponents. We calculate the Lyapunov exponents for timelike geodesics in background metric and photon geodesics in effective metric. It is found that black hole phase transitions can be described by multiple-valued Lyapunov exponents. And its phase diagram can be characterized by Lyapunov exponents and Hawking temperature. Besides, the change of Lyapunov exponents can be considered as order parameter, and exists a critical exponent 1/2 near critical point.
Constraining the spatial curvature with cosmic expansion history in a cosmological model with a non-standard sound horizon
Authors: Stevens Jordan , Khoraminezhad Hasti , Saito Shun
Published: July 2023

Spatial curvature is one of the most fundamental parameters in our current concordance flat ΛCDM model of the Universe. The goal of this work is to investigate how the constraint on the spatial curvature is affected by an assumption on the sound horizon scale. The sound horizon is an essential quantity to use the standard ruler from the Cosmic Microwave Background (CMB) and Baryon Acoustic Oscillations (BAOs). As an example, we study the curvature constraint in an axion-like Early Dark Energy (EDE) model in light of recent cosmological datasets from Planck, the South Pole Telescope (SPT), and the Atacama Cosmology Telescope (ACT), as well as BAO data compiled in Sloan Digital Sky Survey Data Release 16. We find that, independent of the CMB datasets, the EDE model parameters are constrained only by the CMB power spectra as precisely and consistently as the flat case in previous work, even with the spatial curvature. We also demonstrate that combining CMB with BAO is extremely powerful to constrain the curvature parameter even with a reduction of the sound-horizon scale in an EDE model, resulting in ΩK= -0.0058± 0.0031 in the case of ACT+BAO after marginalizing over the parameters of the EDE model. This constraint is as competitive as the Planck+BAO result in a ΛCDM model, ΩK= -0.0001± 0.0018.
Coherent states of the free quantum particle in a viscous medium
Authors: Sazonov S V
Published: July 2023

On the basis of the canonical quantization procedure, the motion of a micro-particle in a viscous medium is considered, where the drag force consists of two components proportional to the first and second degrees of velocity, respectively. The wave function of a particle corresponding to its quantum coherent state is found using the quasi-classical approach. It is shown that due to the viscous of the medium, a static localized domain of the probability density is formed at relatively long times. It is shown that the parameters of this domain contain the information about the parameters of the particle on the input to medium.
Continuous synthesis of artificial speech sounds from human cortical surface recordings during silent speech production
Authors: Meng Kevin , Goodarzy Farhad , Kim EuiYoung , Park Ye Jin , Kim June Sic , Cook Mark J , Chung Chun Kee , Grayden David B
Published: July 2023

Objective. Brain–computer interfaces can restore various forms of communication in paralyzed patients who have lost their ability to articulate intelligible speech. This study aimed to demonstrate the feasibility of closed-loop synthesis of artificial speech sounds from human cortical surface recordings during silent speech production. Approach. Ten participants with intractable epilepsy were temporarily implanted with intracranial electrode arrays over cortical surfaces. A decoding model that predicted audible outputs directly from patient-specific neural feature inputs was trained during overt word reading and immediately tested with overt, mimed and imagined word reading. Predicted outputs were later assessed objectively against corresponding voice recordings and subjectively through human perceptual judgments. Main results. Artificial speech sounds were successfully synthesized during overt and mimed utterances by two participants with some coverage of the precentral gyrus. About a third of these sounds were correctly identified by naïve listeners in two-alternative forced-choice tasks. A similar outcome could not be achieved during imagined utterances by any of the participants. However, neural feature contribution analyses suggested the presence of exploitable activation patterns during imagined speech in the postcentral gyrus and the superior temporal gyrus. In future work, a more comprehensive coverage of cortical surfaces, including posterior parts of the middle frontal gyrus and the inferior frontal gyrus, could improve synthesis performance during imagined speech. Significance. As the field of speech neuroprostheses is rapidly moving toward clinical trials, this study addressed important considerations about task instructions and brain coverage when conducting research on silent speech with non-target participants.
Magneto-optical properties of water and saltwater in presence of a magnetic field
Authors: Dhobi S H , Nakarmi J J , Waiba R , Koirala B , Yadav K , Gupta S P , Das S K , Shah A K , Paudel K , Dahal K , Sah R L , Lemle L D
Published: July 2023

The magneto-optical (transmittance, absorbance, and reflectance) characteristics of water and saltwater in the presence of a magnetic field (0T to 0.880T) are investigated in this study. The authors studies Raman spectra shift and a magneto-optical response of water and saltwater in magnetic fields. In the case of water, the transmittance is high in a high magnetic field, but in the case of saltwater, the transmittance is low at the low wavelength of the spectrum. The transmittance of water was found to be 0.7 percent higher in the presence of a high magnetic field of 0.88T than in the absence of a magnetic field at the wavelength of 651nm–655.67nm. Similarly, under the same magnetic field (0.88T), transmittance of seawater was found to be 0.9 percent higher at 401.44nm and absorbance was found to be 3.4 percent higher at 622.72nm and 646nm. High magnetic fields, on the other hand, have higher absorbance and reflectance in saltwater than 0.222T and 0T. The MO response was found to be larger in water at 0.880T than in saltwater at 0.222T. At 0.880T, the maximal MO response of water and saltwater is reported to be 0.004983 and 0.009804, respectively, at wavelengths of 668.2 nm and 400 nm. When compared to 0T, the intensity ratio of water is deflected more in a high magnetic field than in a low magnetic field, whereas the intensity ratio of saltwater is deflected less in a high magnetic field than in non-magnetic and low magnetic fields.
Optimizing the operation of photovoltaic panels using mathematical regression models
Authors: Rat C L , Ichim-Burlacu C , Bistrian D A
Published: July 2023

Solar (PV) panel models are necessary for the implementation of solar panel control algorithms such as maximum power point tracking. If real-time control is required, these models will be used on microcontrollers and, therefore, will be subject to constraints of memory and execution time: the model implemented on the microcontroller must occupy a memory area as small as possible and the mathematical relationships it contains can be computed in the shortest possible time. Analytical models usually do not fit this criteria, therefore searching for equivalent models which do fit it is required. In this paper, equivalent mathematical models are determined in the MATLAB programming environment based on data obtained by simulating an analytical model in the LabVIEW programming environment. In this paper, the models were obtained by modeling the current distribution in the panel through regression methods, more specifically by using an optimal response surface which has been validated through the resolution of an optimization problem with restrictions. The optimal response surface was used to estimate the extreme values of the power produced by the panel for certain given weather conditions (maximum power in summer and minimum power in winter).
Control algorithm of the unstable 3DOF system
Authors: Erceg D , Grahovac Z , Knezevic B Z
Published: July 2023

The basic characteristics of a system with three degrees of freedom (3DOF) are nonlinearity and instability. An example of such a system is a double pendulum inverted on a moving platform, that is, a pendulum system with two joints and two rods. These characteristics make the system a perfect model for testing various control algorithms such as PID controllers, linear quadrature optimization (LQR) controllers, neural networks, fuzzy logic, etc. This paper presents the mathematical modeling and method for control of the 3DOF system by applying only the force acting on the platform. The system is modeled using Lagrange equations of the second type, which are used as a systematic method for obtaining differential equations of motion systems. To be able to apply the basic concept of control, it is necessary to linearize the system. Differential equations are solved numerically by applying the Runge - Kutta method ode45. A linear quadrature optimization (LQR) controller was used as the controller. The simulation and the results of the proposed control method are verified by computer simulations. This paper presents the difference between a linearized and a non-linearized system. The advantage of the proposed control concept is reflected in the fact that with very small changes it can be extended to the control of many other nonlinear systems.
Analysis of the problems of acquisition of digital photographs intended to determine the required dimensional accuracy of the product
Authors: Turinski D , Svalina I , Šarić T , Lujić R , Havrlišan S
Published: July 2023

In this paper, some of the problems arising from the acquisition of digital photography intended to determine the dimensional accuracy of products are discussed. Different equipment (digital cameras, lenses, and lighting) was used when acquiring photos in different formats. In mechanical engineering, the tolerances of dimensional measurements of products range from a few microns to 100 microns. Based on that, the technical specifications and capabilities of the cameras and lenses used are analyzed. In addition to the sensor, the resolution of the photo is often limited by the lens. Prior to the acquisition of photographs, problems such as lighting, contrast, sharpness, and the problem of central projection are addressed. During acquisition, technical specifications of the lens such as focal length, minimum focusing distance, aperture, and other lens features that cause acquisition problems are considered. This research and analysis led to valuable insights and conclusions that will facilitate the preparation of the acquisition of digital photography to determine the dimensional accuracy of the product.
The case study of new approach to robot programming and layout design by supporting virtual and augmented reality
Authors: Holubek R , Kusá M , Bocák R
Published: July 2023

In currently designed robotic systems, great emphasis is focused to optimal choice of the appropriate position (smart place) of a particular type of industrial robot. Depending on the chosen application, whether it is a handling, technological or assembly operation, it is very important to choose a suitable type of robot and end effector. Many problems in actually deployed production systems arise from the inappropriately chosen kinematic structure of an industrial robot, where either the robot cannot achieve the required production cycle, or its size or load capacity is incorrectly selected for a given type of the operation, or in some cases the robot does not achieve all required robot targets of the future robotic workplace. In the currently available methods of designing future robotic systems, the pre-production phase of designing and creating various robotic simulations scenarios a very important role in order to verify the robot’s reachability to the required positions, as well as eliminate possible collisions states with different peripherals, etc.. This article aims to point out to the new possibilities of deploying modern technologies in the form of the use of virtual and augmented reality in the chosen case study. The authors aim to show and verify in the VR and AR environment the suitability of the selected type of industrial robot for the selected operation, to simulate and validate the proposed robotic trajectories as well as the final robotic Pick and Place operation for the selected case study.
Management of experimental data resulting from the investigation of applications implemented through SAP UI technologies
Authors: Berdie A D , Rob R S , Raţ C L , Berdie A A , Păun A
Published: July 2023

The process of managing data from measurements involves a set of methods and algorithms to explore and analyze them in order to determine specific structures that reproduce as accurately as possible the essence of the information resulting from them. This paper focuses on the statistical processing and interpretation of measurement data sets derived from measurements in web applications using three SAP UI technologies: Web Dynpro ABAP, Floorplan Manager, and CRM WebClient UI. Aspects related to determining the main statistical parameters, eliminating the values affected by gross errors, checking the randomness of the data, determining the distribution functions corresponding to each data sample, and checking the distributions based on concordance tests are considered.
Topological optimization of vice jaws model for pipe clamping
Authors: Mumović M , Šibalić N , Vujović A , Jovanović J
Published: July 2023

This paper presents a model of the clamping vice jaw that is being developed for clamping the aluminium pipes. This model will be used on an available power hack for cutting the pipes to the desired length for further processing. In order to increase the stiffness to weight ratio of a given model, and thus optimize the material usage, the Topology Optimization method is implemented. The geometry of the jaw needs to adjust to the shape of the pipe, so it does not deform it when the clamping force is applied, and also be made from a material softer than aluminium, so that it does not damage the surface of the pipe. These conditions make the jaws a good candidate to manufacture by FDM 3D printing technology, from frequently used ABS material. As this process is a method of Additive Manufacturing, Topology Optimization benefits it not only in material usage but also in production time and cost. The presented procedure has a general character and as such can be applied to many mechanical parts, especially those made by Additive Manufacturing technologies.
Technical and ecological characteristics of utilizing the hydroelectric power potential of HPS “Gornja Drina” in Republic of Srpska
Authors: Kasikovic O , Dobrnjac N , Dobrnjac M , Golubovic D
Published: July 2023

Water has been extensively used as a renewable energy source. Many countries around the globe generally satisfy their demand for energy from precisely this energy source. In many countries of the world, the production of electricity is increasingly being created by hydropower capacities. Global demands for electricity are looking forward to being satisfied mostly from renewable energy sources, especially when it comes to hydropower. This paper presents the planned production of electricity in Republic of Srpska in 2022. The technical characteristics of HPS “Gornja Drina” are also considered, as well as the possible environmental impacts that would occur with the construction of new hydropower plants.
Increasing the fatigue strength of threaded joints of oil and gas equipment by plastic deformation of the thread under high load before make-up
Authors: Kopei V B , Onysko O R , Panchuk V G , Odosii Z M , Kusyi Y M
Published: July 2023

Uneven distribution of stresses in the thread can cause fatigue failure of the joint, usually in the area of the first roots of the thread. This problem is very relevant for shouldered threaded joints of oil and gas equipment, which operate under conditions of significant cyclic loads. One of the ways to equalize the stresses in the thread is plastic deformation of the thread with a high load before make-up. The influence of various methods of such pre-deformation of the tool joint of drill pipes and the connection of sucker rods on the fatigue life in the thread roots of the pin and box has been studied. A method for optimizing the load for pre-deformation was proposed and it was found that the optimal load can increase the fatigue life by 5 times. The study was carried out by finite element analysis of the axisymmetric model in Abaqus/CAE and calculation of the fatigue life from the Brown-Miller dependence using fe-safe.
Cavitation behavior study of the aging heat treated aluminum alloy 7075
Authors: Luca A N , Bordeasu I , Ghiban B , Demian A M , Ghera C
Published: July 2023

Aluminium-based alloy type 7075 is known for its good ductility, high mechanical strength, toughness and high fatigue strength, which is why it is mainly used in the construction of dynamically stressed parts in the structure of airplanes, vehicles and ships. Although it has these qualities, at present its behavior has not been studied at the hydrodynamic stresses that allow it to be used in parts that work in cavitation conditions, such as pump rotors and boat propeller blades. Therefore, the research in this paper highlights the behavior of laminated semi-finished structures and obtained by heat treatment of artificial aging at 180°C, with a maintenance time of one hour. Of the 7075 alloy at the demands generated by the vibrating cavity, created by the standard vibrating device with piezoceramic crystals (frequency of 20 kHz, amplitude of 50 µm and electrical power of 500 W). Analysis based on the curves MDE (t) and MDER (t), of the specific parameters of cavitation erosion MDEmax and MDERs as well as of the macro and microscopic images of the eroded structures of cavitation show that, compared to the delivered state (semi-finished), by the heat treatment applied the microstructure does not change cavitation
Improvement of mechanical properties of bevel gears by nitrocarburizing
Authors: Mihuţ G , Ardelean M
Published: July 2023

The automotive industry is one of the most important consumers of materials and especially metal materials. Competition in this area, technical progress and vehicle requirements require knowledge of the properties of materials, processing technologies that ensure operating requirements, reliability, and aesthetic requirements, with minimum costs.

This work is part of modern trends to improve the surface layers of parts used mainly in the automotive industry and beyond. A nitrocarburizing study is presented on the tapered gears that make up the machine differential, as well as the optimization of the nitrocarburizing technology.

The paper describes the objectives of nitrocarburizing, the materials used for this purpose, ending with the structures and properties obtained after nitrocarburizing.
Deflection Compensation Analysis of a 3-RRS Parallel Mechanism
Authors: Li Lanbin , Chen Qiusheng , Wang Manxin
Published: July 2023

Parallel mechanisms have the advantage of high rigidity, large payload capability, and so on, but the positioning accuracy is affected by the elastic deflection arising from external load and gravity. An approach to improving accuracy by compensating elastic deflection is presented with a 3-RRS parallel mechanism as the research object. The approach is implemented by introducing springs on the moving platform and the limbs. Taking the external load, spring force, and gravity, the mechanical and deflection models are established, which can effectively separate the influence of spring force and gravity on the deflection at the endpoint. In addition, considering the constraints of the mechanism’s operating capacity, the springs’ layout and parameters optimization design are studied based on the compensation effect of springs on the global deflection of the platform. The example shows that the method can effectively compensate for the deflection, and the spring applied on the moving platform has the best compensation effect, which can compensate for 91% of the deflection.
Additive Manufacturing of Silicon Oxycarbide Ceramics with Minimal Surface Structures
Authors: Li Jinghan , Shi Yu , Cao Lei , Zhang Zhuoqing , Zhang Xing
Published: July 2023

The traditional ceramic powder sintering forming method severely limits the performance of the fabricated parts. Many new solutions have been achieved by precursor derived ceramics (PDC). Silicon oxycarbide ceramics as one of them has many performance advantages such as excellent mechanical properties, low density, excellent thermal stability, low thermal conductivity, and resistance to thermal shock and corrosion. In this paper, a photosensitive polysiloxane resin (PPR) with excellent light curing properties was prepared, which has high precision in the process of additive manufacturing. In addition, samples with minimal surface features in different porosity were fabricated. The compressive strength of the structure with 85%, 75%, and 65% porosity was about 9.51 MPa, 13.76 MPa, and 21.69 MPa, respectively. These porous silicon oxycarbide ceramics are likely to have a wide range of potential applications in aerospace, aviation, and other fields.
First-principle calculation of hydrogen adsorption on the surface of Ni3Al (110)
Authors: Li Fu , Du Xiaoming , Liu Jide
Published: July 2023

Nickel-based superalloy has good mechanical properties and corrosion resistance, and is widely used in the oil and natural gas industry. However, hydrogen brittle is a serious problem that the application of nickel-based superalloy must face. In this study, the first principle calculation method based on density functional theory was used to calculate the adsorption energy of the molecules of hydrogen and hydrogen atoms on the Ni3Al (110) surface. The calculated results show that the adsorption of hydrogen molecules on the surface of Ni3Al (110) is physical adsorption. The preferential adsorption site of hydrogen molecules is at the top site of Ni atoms, and Ni can promote the dissociation of hydrogen molecules. Hydrogen atoms tend to adsorb in the bridge, and the Ni-Ni bridge site is the preferential adsorption site.
Experimental study on DC corona charging characteristics of powder particles with different properties
Authors: Fang Guofeng , Chen Liang , Shi Weidong , Xie Changyou , Zhang Kaichuang
Published: July 2023

In this paper, the charging characteristics of powder particles with different properties under DC discharge corona conditions were studied experimentally. The influence of different charging voltages and different charging structures on the charge-mass ratio of particles was analyzed through ELPI measurement. The experimental results show that the far-field charging structure of the electrode can effectively charge powder materials like Graphite micro powder, copper sulfide, talcum powder, and porous material (Si Al) within the particle size range of 0.1 μm−10 μm; When there is no streamer or spark between the charging electrode and the grounding electrode of the charging device, the higher the charging voltage is, the higher the degree of air ionization is, and the better the charging effect on particles is; Under the same charge condition, the charge-mass ratio of particles decreases with the increase of particle size.
Numerical Simulation Analysis of Three-phase Submerged Arc Furnace Using the Multi-field Method
Authors: Zhao Jincheng , Zhang Xiuheng
Published: July 2023

To reveal the distribution law of the multi-physics field in the smelting of the submerged arc furnace, the temperature distribution in the furnace for a given electrode diameter was studied, and the multi-physics field coupling model of the submerged arc furnace was established, based on Maxwell’s equation, Ohm’s law, numerical analysis of fluid governing equations and heat transfer mechanism. The results show that the current density is mainly affected by the skin effect on the surface of the electrode, with a maximum value of 35000 A/m2; the Joule heat is mainly concentrated at the bottom of the electrode in the material layer; the maximum value of the magnetic flux density is at the electrode pole center circle, about 0.02 T; the flow of the fluid in the molten pool is affected by the Lorentz force and gravity, and the distribution of the Lorentz force in the slag layer is more obvious; the maximum temperature in the furnace reaches 2500°C and is located at the bottom of the electrode, which is gradually transferred from the material layer to the slag layer.
Numerical simulation study on progressive bending of magnesium alloy grid panel
Authors: Yun Hongjie , Wang Zhongtang , Liang Haicheng , Li Yanjuan
Published: July 2023

Research and development of magnesium alloy integral panel forming technology to replace existing titanium alloy and aluminum alloy panel materials are of great significance for saving aluminum and titanium resources. The material flow law during progressive bending technology of panel (PBTP) was analyzed by numerical simulation study. The deformation forming parameters of PBTP for Mg alloy grid panel and panel size control parameters are defined. The process parameters include deformation temperature, bending deformation coefficient, and reduction speed. The size and accuracy control parameters include the width of the bending die, pressing height, and feed rate. The panel radius was related to the width of the bending die and the height of the reduction. With increase of forming temperature, maximum damage coefficient, maximum equivalent stress and maximum equivalent strain reduce. With increase in bending deformation coefficient, maximum damage coefficient, maximum equivalent stress and maximum equivalent strain increase. Based on simulation and experimental results, reasonable forming parameters for PBTP of AZ31 Mg alloy grid panel was obtained. Magnesium alloy panel components were successfully processed by progressive bending technology. The influence of die width and pressing height on panel radius was analyzed. The numerical simulation results were consistent with experimental results. The maximum relative error was 3.5%.
Damage formation and force analysis of barrels
Authors: Ji Lu , Xu Zhao , Pan Qihua , Zhang Hong
Published: July 2023

The barrel is one of the important parts of artillery. At the same time, when firing, the bore needs to withstand the high temperature and high pressure powder gas as well as the impact and friction of the projectile, and different damage forms such as cracks, wear and dechromium on the bore will appear. However, the wear of the bore is one of the main reasons for the error of the firing accuracy, and it can even cause other security risks. In this paper, the common damage formation and the force on the tube bore body during the firing were analyzed, so as to further estimate the life of the body tube and provide a basis for the structural health monitoring of the body tube and other key components.
Research on Defects Control of Niobium Tungsten Alloy by Laser Welding
Authors: Xu Fei , Li Yulong
Published: July 2023

The laser welding experiment of Nb521 niobium-tungsten alloy with 1.0mm thickness was carried out, and the effects of different welding edge preparation states, including fast wire cutting + milling and slow wire cutting + no milling, on the weld formation were analyzed. The results show that the laser weldability of the niobium-tungsten alloy is very good. The welding parameters are in a wide range, and good weld formation can be obtained easily. The effect of the welding edge preparation states on weld formation is very small, and all of the welded joints are broken in the base metal zone far away from the weld beam. Based on laser welding, the forming analysis of argon arc repair welding was carried out. The defects such as cracks and oxidation could be controlled effectively by optimizing the welding process. When the ratio of argon arc repair welding is in the range of 30% to 50%, the welded joints still have good tensile properties. The average tensile strength reaches 98.9% of the base metal and the average elongation after fracture reaches 83.8% of the base metal.
CNC machining optimization of hydro-turbine runner blade based on VERICUT
Authors: Han Xuesong , Li Jianwen , Liu Qibo , Lu Shangping
Published: July 2023

Aiming at the problem of low production efficiency caused by the unreasonable setting of cutting parameters for CNC machining of hydro-turbine runner blade, the Force module of VERICUT software is used to analyze and compare the cutting force, the cutting power, and the material removal rate of the blade under different cutting parameters, find the cutting parameters that can give full play to the machining capacity of the machine tool, and use the optimization function of Force to automatically adjust the feed speed in the machining program. The test results show that after the optimization of cutting parameters, the production efficiency of the NC machining program is significantly improved, and the cutting power of the machine tool spindle is stable.
Fracture failure analysis and prevention of carbon fiber thin wall crossbar
Authors: Rong Jian , Lv Haiqing , Sun Zijie , Xu Ting , Chen Xuesheng , Zhang Youyi , Zhang Zhipeng , Feng Tao
Published: July 2023

The fracture failure of a crossbar occurred in a routine deployment test of a satellite ring antenna truss structure. In this study, the fracture cause of the carbon fiber thin wall crossbar was analyzed using body microscope observation, scanning electron microscope observation, metallographic analysis, hardness analysis, XRD analysis, and other methods. The analysis results show that the failure bar had interlaminar damage and local crack or breakage before this deployment test. This defect has further expanded and intensified in the multiple deployment tests of the circular antenna, resulting in the gradual decline of the local stiffness of the crossbar, and finally the buckling failure. By using the bottom plate reflection method to carry out non-destructive testing on the rod, it can effectively avoid false inspection and missing inspection of defects.
A control method of excess material in cold plate processing with a runner
Authors: Li Hui , Wang Tao
Published: July 2023

Cooling plates are widely used in modern electronic equipment and usually contain channels with a complex structure. Welding, heat treatment, machining, and turnover on cooling plates are often accompanied by waste such as mental swarf. The waste could enter the plates and block the liquid inlets or outlets, thereby affecting the normal operation of electronic equipment. In light of this, we design a labyrinth seal system for heat treatment and a sealing block for mechanical processing with proper techniques. The research results show that waste can be prevented from entering the channel and help keep the entire cooling system clean.
Secondary-phase Transformation of Duplex Stainless Steels during Industrial Manufacturing
Authors: Li Xianchao
Published: July 2023

A new type of lean S32205 duplex stainless steel was studied on its secondary phase formation during industrial manufacturing. Different from the common S32205 duplex stainless steels, such lean S32205 duplex stainless steels contain more carbon and nitrogen elements, which promotes the formation of Cr2N and Cr23C6 secondary precipitations. The secondary-phase transformation is preferred at boundaries, either in the ferrite phase or at interphase interfaces after rolling, and even a few secondary precipitates can be found at the as-cast ferrite grain interiors as well. The influence of the secondary phase transformations on pitting resistance and hot ductility was investigated.
Measuring the Tension Stress in Fixed Boundary Membrane Structure by Vibration Method
Authors: Li Guanjun , Xu Zhihong , Chen Tao
Published: July 2023

In this paper, a linear relationship between the frequency of membrane structures and their inner tension stress has been studied. The analytical relationships between the vibration frequency and the tension stress were obtained, and the results were verified by experiment and finite element simulations.
Dynamic Characteristics of Thin Film Structure with Concentrated Mass
Authors: Cheng Jingsong , Wang Sheng , Nie Ying , Song Lin
Published: July 2023

Aiming at the design and analysis of flexible film building rigid flexible large complex structure system, this paper carried out the simulation analysis of dynamic characteristics of thin film structure with concentrated mass. The structural connectors with high stiffness and relatively concentrated mass are simplified as concentrated mass. The flexible thin film structure is simplified as a biaxially tensioned cross film material sample. The influences of pretension, quality, and concentrated mass of the size on the natural frequency of cross film material samples are analyzed. The results show that the natural frequency of the sample increases with pretension, decreases with the quality of the concentrated mass, and increases with the side length of the connection between the concentrated mass and the sample. The fundamental frequency of the sample is independent of the height of the concentrated mass, but the second frequency decreases with the height of the concentrated mass. The research results provide a theoretical basis for the overall design and analysis of building film structure and the further dynamic experiments of film material samples with concentrated mass.