bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of rolled fibrous microstructure on fatigue properties of extruded Cu-5Al planar micro springs
Authors: Li F Y , Wang X B , Ma S J , Dong X H , Zhang X P
Published: August 2023

Planar micro spring is an important elastic component in microelectromechanical system devices, and one of its main failures is fatigue. In this work, a new method to improve the cycles of a planar micro spring by introducing pre-rolled fibrous microstructure was proposed. Cu-5Al alloy billets with a fibrous microstructure rolled at room temperature with a reduction ratio of 70% were obtained. Three types of planar micro springs with fibrous microstructure were prepared through extrusion by varying the angle between the fibrous microstructure direction and the extrusion direction. Fatigue tests were conducted using a customized micro-fatigue test system. The best fatigue performance was obtained by preparing the micro springs with the fibrous microstructure direction perpendicular to the extrusion direction, while the worst fatigue performance was obtained by preparing the planar micro springs with the fibrous microstructure direction parallel to the extrusion direction. The fibrous microstructure direction affected the local strain in the micro springs. The fibrous microstructure slightly affected the location of the crack initiation region but significantly affected the area of crack initiation and steady-state expansion region of the micro spring. The fatigue life cycle of extruded Cu-5Al alloy planar micro spring with the pre-rolled fibrous microstructure improved by 58% more than that of extruded Cu-7Al alloy planar micro spring without the pre-rolled fibrous microstructure. Micro spring fatigue life cycle decreased with increasing strain amplitude. This work provides a new approach for preparing planar micro springs with high fatigue performance.
Capillary enhanced phase change in a microfabricated self-oscillating fluidic heat engine (SOFHE)
Authors: Karami Nooshin , Tessier-Poirier Albert , Leveille Étienne , Amnache Amrid , Frechette Luc G
Published: August 2023

This paper reports the design, fabrication, and characterization of a miniaturized version of a self-oscillating fluidic heat engine (SOFHE) for thermal energy harvesting. This new design includes capillary corners of a square cross-section, as well as an etched capillary path on the bottom wall that improves the performance in terms of stability and mechanical power owing to the enhanced phase change. The engine consists of a vapor bubble trapped in a microchannel by an oscillating liquid plug (acting as a piston) set in motion by periodic evaporation and condensation in the vapor bubble. The underlying physics of the oscillations is similar to those of a single-branch pulsating heat pipe. The channel is microfabricated by anodically bonding a grooved glass wafer (top and sidewalls) to a silicon wafer (bottom wall). To further increase the phase change, two more channels are fabricated with an etched capillary path on the bottom wall at two different widths of 25 and 50 µm and a depth of 100 µm. This is the first miniaturized SOFHE that generates a reliable amplitude in the millimeter range. By measuring the change in the volume of the vapor bubble and the frequency, we calculated the change in pressure using the momentum balance on the liquid plug, and then calculated the work, mechanical power, and power density. We observed that the addition of the etched capillary path at a width of 50 µm increased the amplitude (from 1.6 to 4 mm) leading to a fivefold increase in the generated power (from 8 to 40 µW). This study opens a new path towards designing different wicking structures to maximize the amplitude and power density of the SOFHE, making it a promising thermal energy harvester to power wireless sensors.
Transition metal-doped V-shaped RuO2 103 nanotwins as highly active electrocatalysts for enhanced oxygen evolution in acidic media
Authors: Zhao Huining , Wu Jingjing , Tang Xin
Published: August 2023

Efficient and stable catalysts for the oxygen evolution reaction (OER) in acidic environments are essential for hydrogen production through electrolysis. The paper reported the transition metal-doped RuO2 103 nanotwins (RuO2 103-NTs), as cost-effective and high-performance catalysts for acidic OER. The MRu-VO defect models were constructed by introducing transition metal (Ag, Mn, Fe, Co, Cu, and Zn) doped surfaces. Thereinto, the AgRu-VO doped structure exhibited remarkable OER activity in acidic conditions, achieving a reduced overpotential of 0.37 eV. Furthermore, we investigated the synergistic effect of the Ag and oxygen vacancies (VO) in conjunction with grain boundaries. Above results revealed that an increase in the content of Ag and VO resulted in a decrease in structural stability, leading to a more disordered structure. By analyzing the adsorption energy, energy band center and charge transfer in bimetallic-doped NTs, we observed that the presence of MRu-AgRu-VO (M = Mn, Co, Fe) significantly promotes the positive shift of d band center and the increase of charge transfer. This effect ultimately led to a decrease in the overpotential of the rate-determining step to 0.27 eV, thereby enhancing the intrinsic activity of RuO2.
Wideband single-feed dual circularly polarized multi-beam transmitarray antenna based on receiver–transmitter metasurface
Authors: Wu Lin-Xiao , Chen Ke , Yang Wei-Xu , Zheng Yi-Lin , Zhao Junming , Feng Yijun
Published: August 2023

In this paper, a novel metasurface (MS) as well as a generalized dual-circular-polarized (CP) decoupled modulating method are proposed. The proposed MS can realize high-efficiency dual-spin transmissions with equal-magnitude upon left handed circular polarization (LCP) incidence across 9–12.5 GHz. This MS is constructed based on the receiver–transmitter configuration, and the receiver layer composed of an LCP patch resonator while the transmitter layer is a linearly polarized patch resonator. Rotating the receiver and transmitter patches separately can impose identical and conjugated geometric phase modulations for the dual-CP transmission waves, respectively. Hence, through an elaborate combination of the dual geometric phases, totally decoupled and dispersion-less phase modulations for transmitted dual-spin waves can be obtained. As the proof of its uses in practical applications, we have designed a single-feed dual-CP dual-beam transmitarray antenna (TA) and a dual-CP quad-beam TA. The second TA is also fabricated and tested. The measured results are consistent with the simulated results, showing that the TA achieves peak aperture efficiency of 49% at 9.5 GHz, with 1 dB gain bandwidths (BWs) of the dual-CP quad-beams all larger than 24.5% while 3 dB axial ratio BWs all larger than 54.5%. The proposed wideband and high-gain dual-CP multi-beam TAs may have promising prospects for many applications such as vehicle-satellite communication systems, satellite broadcasting and coverage systems.
Tube inner wall defect detection method based on rotary scanning micro laser distance sensor
Authors: An Yang , Liu Xuxiang , Pang Ran , Zhu Xixin , Wang Xiaocen , Qu Zhigang
Published: August 2023

In this paper, an inspection device to detect the inner wall defects of oil tubes is proposed, mainly consisting of a micro laser distance sensor and a stepper motor. When the inspection device moves along the axial direction inside the tube, the stepper motor drives the micro laser distance sensor to rotate and scan the inner wall of the tube so that the coordinate data of the 3D point cloud can be obtained. In order to obtain the pose transformation matrix for the laser distance sensor coordinate system with respect to the device flange coordinate system, a particle swarm optimization algorithm is introduced. Finally, experiments are carried out on two real oil tubes and point cloud data are obtained which provide 3D information about the inner walls of the tubes. The measuring error of tube eccentric wear is within 0.2 mm, which verifies the effectiveness of this novel method.
Deep learning-based fluorescence image correction for high spatial resolution precise dosimetry
Authors: Nomura Yusuke , Ashraf M Ramish , Shi Mengying , Xing Lei
Published: August 2023

Objective. While radiation-excited fluorescence imaging has great potential to measure absolute 2D dose distributions with high spatial resolution, the fluorescence images are contaminated by noise or artifacts due to Cherenkov light, scattered light or background noise. This study developed a novel deep learning-based model to correct the fluorescence images for accurate dosimetric application. Approach. 181 single-aperture static photon beams were delivered to an acrylic tank containing quinine hemisulfate water solution. The emitted radiation-exited optical signals were detected by a complementary metal-oxide semiconductor camera to acquire fluorescence images with 0.3 × 0.3 mm2 pixel size. 2D labels of projected dose distributions were obtained by applying forward projection calculation of the 3D dose distributions calculated by a clinical treatment planning system. To calibrate the projected dose distributions for Cherenkov angular dependency, a novel empirical Cherenkov emission calibration method was performed. Total 400-epoch supervised learning was applied to a convolutional neural network (CNN) model to predict the projected dose distributions from fluorescence images, gantry, and collimator angles. Accuracy of the calculated projected dose distributions was evaluated with that of uncorrected or conventional methods by using a few quantitative evaluation metrics. Main results. The projected dose distributions corrected by the empirical Cherenkov emission calibration represented more accurate noise-free images than the uncalibrated distributions. The proposed CNN model provided accurate projected dose distributions. The mean absolute error of the projected dose distributions was improved from 2.02 to 0.766 mm·Gy by the CNN model correction. Moreover, the CNN correction provided higher gamma index passing rates for three different threshold criteria than the conventional methods. Significance. The deep learning-based method improves the accuracy of dose distribution measurements. This technique will also be applied to optical signal denoising or Cherenkov light discrimination in other imaging modalities. This method will provide an accurate dose verification tool with high spatial resolution.
Comparing neutron and helium ion irradiation damage of REBa2Cu3O
7−δ
coated conductor using x-ray absorption spectroscopy
Authors: Adams K , Iliffe W , Nicholls R J , He G , Diaz-Moreno S , Mosselmans F , Fischer D , Eisterer M , Grovenor C R M , Speller S C
Published: August 2023

Understanding the effects of high energy neutron damage on REBa2Cu3O

7
−
δ

(REBCO) coated conductor is of vital importance for the design of the magnetic confinement systems for compact nuclear fusion power plants. However, neutron irradiation campaigns can only be carried out in a few facilities, and the experiments are very slow and expensive partly because the samples become radioactive. Ion irradiation provides an easily accessible alternative route to studying the effects of radiation on high temperature superconductors, which not only increases the volume of technical data that can be obtained but also enables more complex experiments such as in situ cryogenic irradiation. The question is, does ion damage offer a good proxy for neutrons? Here we use high energy resolution fluorescence detected x-ray absorption spectroscopy to probe the effects of fast neutron irradiation on the local environment around the copper ions in the REBCO layer of coated conductor tapes. We find that the spectral changes are similar to those induced by helium ion irradiation, suggesting that both projectiles produce the same types of structural defect in the REBCO lattice, although there is some evidence of an additional type of defect present in the sample heavily damaged by He+ ion irradiation. It is also shown that the linear degradation of superconducting transition temperature (T
c
) of coated conductors with the calculated number of displacements per atom occurs at the same rate for neutrons and helium ions. Together these results provide new evidence suggesting that helium ions can emulate neutron point defect damage in REBCO high temperature superconductor reasonably well, increasing confidence that helium ions could be used as a useful proxy for neutrons in future experiments.
Measuring magnetic 1/f noise in superconducting microstructures and the fluctuation-dissipation theorem
Authors: Herbst M , Fleischmann A , Hengstler D , Mazibrada D , Münch L , Reifenberger A , Ständer C , Enss C
Published: August 2023

The performance of superconducting devices like qubits, superconducting quantum interference devices (SQUIDs), and particle detectors is often limited by finite coherence times and

1

/

f

noise. Various types of slow fluctuators in the Josephson junctions and the passive parts of these superconducting circuits can be the cause, and devices usually suffer from a combination of different noise sources, which are hard to disentangle and therefore hard to eliminate. One contribution is magnetic

1

/

f

noise caused by fluctuating magnetic moments of magnetic impurities or dangling bonds in superconducting inductances, surface oxides, insulating oxide layers, and adsorbates. In an effort to further analyze such sources of noise, we have developed an experimental set-up to measure both the complex impedance of superconducting microstructures, and the overall noise picked up by these structures. This allows for important sanity checks by connecting both quantities via the fluctuation-dissipation theorem. Since these two measurements are sensitive to different types of noise, we are able to identify and quantify individual noise sources. Furthermore, our measurements are not limited by the quantum noise limit of front-end SQUIDs, allowing us to measure noise caused by just a few ppm of impurities in close-by materials. We present measurements of the insulating

SiO

2

layers of our devices, and magnetically doped noble metal layers in the vicinity of the pickup coils at

T
=
40

mK

−
800

mK

and

f
=
1

Hz

 
−
100

kHz

.
Real-time self-compensation design of suspended FBG sensor in dynamic measurement
Authors: Zhao Kexin , Yu Junchang , Zhang Hongquan
Published: August 2023

In this paper, a Kalman filtering method incorporating an indentation model is proposed for noise and indentation problems during dynamic thickness measurement of suspended fiber Bragg gratings sensors. This method not only plays a filtering estimation effect, but also can effectively compensate the indentation error in the contact thickness measurement process. The relevant experimental results show that the method can obtain better compensation values for parts under measurement of various materials and thicknesses, the compensated thickness is in good agreement with the true value, and the average absolute percentage error is not more than 5%. The method is also highly applicable to dynamic measurement processes with high noise levels. Finally, the designed filtering compensation method is applied to an example of scanning sample morphology and achieves excellent results.
Numerical modeling to predict threshold fluence for material ejection in Laser-Induced forward transfer of metals
Authors: Muniyallappa Aanjinappa , Chandra Harish , Marla Deepak
Published: August 2023

Laser-induced forward transfer (LIFT) uses a pulsed laser beam to propel material from a donor (containing a glass coated with a thin material film) onto a receiving substrate, resulting in pixellated material deposition. The deposition characteristics depend on the material ejection modes that vary with film thickness and laser parameters. This study develops a computational model based on the finite volume method for LIFT of gold films using nanosecond pulses, which captures two different ejection modes for droplet depositioncap ejection and jet ejection. The model computes the temperature distribution and predicts potential ejection regimes for different film thicknesses, providing an understanding of the material removal process. Cap ejection occurs at lower laser fluences when the entire film thickness in the irradiated zone is in the molten phase. In comparison, jet ejection occurs at higher laser fluences caused by vapor pocket formation at the glass-film interface. The model predicts threshold fluences with greater than 90% accuracy for film thickness less than 583 nm. However, for the film thickness of more than 583 nm, the simulations underpredict the threshold fluence, suggesting that laser absorption by the film decreases due to vapor formation at the glass-film interface. Besides, it is observed that higher fluences can cause melting and vaporization of the glass at the interface leading to possible contamination of the deposited material. The proposed model can be used to choose the operating window for laser parameters for droplet deposition in LIFT, which otherwise is challenging using experiments.
Operational calculus for Hilfer-Prabhakar operator Applications to inverse problems
Authors: Javed Sehrish , Malik Salman A
Published: August 2023

Mikusiński's operational calculus has proven to be a powerful tool for tackling various fractional order differential equations. Notably, it has been extended to encompass the Hilfer-Prabhakar fractional order operator. By employing this operational calculus, we have been able to recover and connect previously derived results pertaining to the Hilfer, Riemann-Liouville, and Caputo operators. Furthermore, we address two inverse problems that involve determining space and time dependent source terms and diffusion concentration. Using our operational calculus results, we obtain series solutions for these inverse problems. It is essential to note that the inverse problems belong to the class of ill-posed problems according to Hadamard's definition. To establish the validity and uniqueness of the solutions to both inverse problems, we rigorously prove the existence and uniqueness results. Additionally, we provide specific examples of inverse problems, thereby illustrating the practical applications and versatility of the operational calculus approach.
Comprehensive analysis of relativistic embedded class-I exponential compact spheres in f(R, ϕ) gravity via Karmarkar condition
Authors: Asghar Zoya , Malik Adnan , Shamir M Farasat , Mofarreh Fatemah
Published: August 2023

In this article, we use the prominent Karmarkar condition to investigate some novel features of astronomical objects in the f(R, ϕ) gravity; R and ϕ represent the Ricci curvature and the scalar field, respectively. It is worth noting that we classify the exclusive set of modified field equations using the exponential type model of the f(R, ϕ) theory of gravity f(R, ϕ) = ϕ(R + α(e
β
R − 1)). We show the embedded class-I approach via a static, spherically symmetric spacetime with an anisotropic distribution. To accomplish our objective, we use a particular interpretation of metric potential (g

rr
) that has already been given in the literature and then presume the Karmarkar condition to derive the second metric potential. We employ distinct compact stars to determine the values of unknown parameters emerging in metric potentials. To ensure the viability and consistency of our exponential model, we execute distinct physical evolutions, i.e. the graphical structure of energy density and pressure evolution, mass function, adiabatic index, stability, equilibrium, and energy conditions. Our investigation reveals that the observed anisotropic findings are physically appropriate and have the highest level of precision.
In situ calibrated angle between the quantization axis and the propagating direction of the light field for trapping neutral atoms
Authors: Guo 郭 Rui-Jun 瑞军 , He 何 Xiao-Dong 晓东 , Sheng 盛 Cheng 诚 , Wang 王 Kun-Peng 坤鹏 , Xu 许 Peng 鹏 , Liu 刘 Min 敏 , Wang 王 Jin 谨 , Sun 孙 Xiao-Hong 晓红 , Zeng 曾 Yong 勇 , Zhan 詹 Ming-Sheng 明生
Published: August 2023

The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique relies on applying a bias magnetic field precisely parallel to the wave vector of a circularly polarized trapping laser field. However, due to the presence of the vector light shift experienced by the trapped atoms, it is challenging to precisely define a parallel magnetic field, especially at a low bias magnetic field strength, for the magic-intensity trapping of 85Rb qubits. In this work, we present a method to calibrate the angle between the bias magnetic field and the trapping laser field with the compensating magnetic fields in the other two directions orthogonal to the bias magnetic field direction. Experimentally, with a constant-depth trap and a fixed bias magnetic field, we measure the respective resonant frequencies of the atomic qubits in a linearly polarized trap and a circularly polarized one via the conventional microwave Rabi spectra with different compensating magnetic fields and obtain the corresponding total magnetic fields via the respective resonant frequencies using the Breit–Rabi formula. With known total magnetic fields, the angle is a function of the other two compensating magnetic fields. Finally, the projection value of the angle on either of the directions orthogonal to the bias magnetic field direction can be reduced to 0(4)° by applying specific compensating magnetic fields. The measurement error is mainly attributed to the fluctuation of atomic temperature. Moreover, it also demonstrates that, even for a small angle, the effect is strong enough to cause large decoherence of Rabi oscillation in a magic-intensity trap. Although the compensation method demonstrated here is explored for the magic-intensity trapping technique, it can be applied to a variety of similar precision measurements with trapped neutral atoms.
Electric field intensity measurement by using doublet electromagnetically induced transparency of cold Rb Rydberg atoms
Authors: Gong 宫 Ting 廷 , Shi 师 Shuai 帅 , Ji 姬 Zhonghua 中华 , Guo 郭 Guqing 古青 , Sun 孙 Xiaocong 小聪 , Tian 田 Yali 亚莉 , Qiu 邱 Xuanbing 选兵 , Li 李 Chuanliang 传亮 , Zhao 赵 Yanting 延霆 , Jia 贾 Suotang 锁堂
Published: August 2023

We demonstrate a simple method to measure electric field intensity by using doublet electromagnetically induced transparency (EIT) spectra of cold Rb Rydberg atoms, where the frequency of the coupling laser does not need to be locked. Based on the Stark splitting of the Rb Rydberg state, 10D3/2, under electric fields and the corresponding calculated polarizabilities, the real electric field intensity is calculated using the difference in radio-frequency diffraction between two acousto-optic modulators, which acts as a frequency criterion that allows us to measure the electrical field without locking the coupling laser. The value measured by this simple method shows a good agreement with our previous work [Opt. Express
29 1558 (2021)] where the frequency of the coupling laser needs to be locked with an additional EIT spectrum based on atom vapor and a proportional–integral–differential feedback circuit. Our presented method can also be extended to the measurement of electric field based on hot Rydberg atom vapor, which has application in industry.
Fatigue strength analysis of semi-submersible platforms based on wide-band stress
Authors: Zhou Chenyan , Zhang Yahong , Chen Ling , Wu Zhongxin
Published: August 2023

As the focus of ocean resource exploitation shifts from shallow sea to ultra-deep sea, semi-submersible platforms are far away from the coastline for a long time. The semi-submersible platform structure is more prone to fatigue damage under complex sea conditions. The stress range and peaks are considered in the conventional frequency domain spectral method to obey the narrow-band distribution, which makes the results of fatigue assessment tend to be conservative. To solve the problems above, a wide-band fatigue assessment method based on Rice distribution is proposed from the perspective of stress distribution. Different methods are used to solve the error functions involved in fatigue calculations to obtain different approximate equivalent stress models. Finally, the broadband fatigue analysis of a semi-submersible platform in the South China Sea was carried out under different models, and the results showed that: The error of the wide-band fatigue calculation based on Rice distribution is related to the selected equivalent stress model, and a suitable model needs to be selected according to the bandwidth coefficient of the structure. The results obtained provide a reference for the safety assessment of pipelines in service. The research provides a reference for the fatigue assessment of semi-submersible platforms under random broadband loads.
Gel-assisted Welding of Epoxy Composite with Ethylene Glycol Mixed Catalyst
Authors: Li Xiuzhao
Published: August 2023

Effective and high-strength welding of thermosetting composites is badly in demand and always a challenge in industrial applications. Here, a gel-assisted welding method was proposed for traditional epoxy composites using a gel of 1,5,7-triazabicyclo [4.4.0] dec-5-ene mixed with ethylene glycol (TBD/EG gel) for pretreatment. Firstly, the influence of TBD/EG gel thickness, pretreatment time, pretreatment temperature, and pretreatment after soaking for the welding strength of the epoxy composite was studied. Then, the appropriate TBD/EG gel thickness (2 mm) and TBD/EG gel pretreatment conditions (140 °C for 60 min) were obtained. Compared to the different pretreatment methods for welding, the welding of TBD/EG gel pretreatment is feasible.
Achieve hybrid energy harvesting based on the internal resonance of a two-degree-of-freedom cantilever beam
Authors: Li Yuanhua , Han Minglei , Chen Xinhai
Published: August 2023

Taking a cantilever beam with two-degree-of-freedom (DOF) as an example, this paper studies the energy transfer mechanism between the vibration DOF and the rotation DOF, proposes a hybrid energy harvesting scheme, establishes the dynamic equation and solves it. Through the simulation of the analytical equation, it is found that under the condition of internal resonance of two DOFs, the two nonlinear peaks on the rotation DOF are very conducive to energy harvesting in the wide frequency domain. Furthermore, the influence of excitation amplitude, electromechanical coupling coefficient, time domain constant and other parameters on the resonance frequency and amplitude response of the energy harvesting system is studied.
Detection of TNT wastewater by the molecular imprinted porous membrane
Authors: Ma Baohong , Du Xuefeng , Li Zhenkai , Shao Yusong
Published: August 2023

In this paper, the preparation scheme of TNT molecularly imprinted porous film and the scheme of TNT identification and detection in wastewater are designed by means of molecular imprinting technology. The molecularly imprinted porous film material was prepared by the self-assembly method, and the TNT residue adsorption was detected by a UV-visible spectrophotometer. The concentration of TNT waste liquid was calculated by absorbance, and the effect of the deviation of ultraviolet spectra of different contents of TNT waste liquid was discussed. The results show that the molecularly imprinted films have high adsorption and specific recognition effect on TNT, which can be used for rapid and sensitive detection of TNT in the waste liquid.
Study on Effect of Hot Rolling Process Lubricant on Rolling Force and Thickness of Q235A Strip Steel
Authors: Tian Yuting , Li Yan , Lei Xia , Li Qihang
Published: August 2023

Taking the Q235A plate and strip as the research object, hot rolling experiments were carried out under different concentrations and compositions of hot rolling process lubricants, and the effect of different lubrication conditions on the rolling effect of the Q235A plate was studied. The experimental results show that the processing lubricant used for 3 # and 4 # samples has the best effect, and the thickness of the steel plate rolled with 10% lubricant is thinner than that with 5% lubricant. When the concentration of lubricant is 10%, the maximum reduction of the third pass rolling force is 24.4%. The rolling force with oil lubrication is 21% lower than that without oil lubrication.
Experimental Study on the New Type of Connecting Nodes of Prefabricated Stairs Using Flexible Grouting Material
Authors: Zhang Shoufeng , Huo Wenying , Liu Ke , Yao Yuan , Sun Qiang
Published: August 2023

In recent years, prefabricated buildings have been developing positively in China. Prefabricated concrete stairs are widely used in prefabricated concrete buildings because of their quick construction, convenient handling, reduced cost, and premium appearance. They also have promising application potential in cast-in-place concrete structures and steel buildings. The stairs are important escape routes during earthquakes and play the role of “safety islands.” Therefore, the study on the seismic performance of connecting nodes of prefabricated concrete stairs is significant. For a new flexible-hinge connecting node of the prefabricated stairs with flexible grouting material (FGM), the low-frequency cyclic loading test is carried out in this paper to study the stress performance of the end nodes of the stairs under in-plane and out-of-plane low-frequency cyclic loading. The results show that the new flexible-hinge connecting nodes of the prefabricated concrete stairs have moderate bearing capacity and stiffness, which can mitigate the effect of diagonal bracing under small and medium earthquakes and dissipate energy to a certain extent.
Preparation of Mesoporous γ-Alumina from Red Mud Waste
Authors: Gao Tianyi , Zhong Li
Published: August 2023

In this paper, a novel green and cost-effective synthesis method in this field is presented. Mesoporous γ-alumina was obtained by inorganic in situ crystallization, and sodium aluminate as an aluminum origin was abstracted from red mud. The influence mechanism of the reactant ratio of NaHCO3 to NaAlO2, the reaction temperature and the concentration of the template was systematically investigated. As indicated by the results, the obtained mesoporous γ-alumina possesses extensive specific surface areas, narrow pore size distribution, nearly spherical particle morphology and wormlike structure pores. This green and economical synthesis method can be used for the preparation of alternative mesoporous or various porous materials as well.
Deterioration of metal and paper caused by camphor wood: a noticeable phenomenon in conservation
Authors: Shen Jingyi
Published: August 2023

Although welcomed and used as storage materials by many museums, camphor wood shows a potential risk to museum collections due to its strong smell. Camphor wood was proved harmful to metals in the author’s previous studies, but since the last study about camphor wood reported by the author, the camphor wood samples have not experienced the Oddy test again for two years, so their harm to metals is unknown at the current stage. Meanwhile, there is no standard or specific method for learning the materials’ effect on organics. The present work focuses on the above situation. Camphor wood samples of different species and aged for different years were tested in this study. Their effect on metals was assessed by performing the Oddy test. On the other hand, a series of mechanical tests were conducted to learn the camphor wood samples’ effect on paper samples commonly used in Chinese calligraphy and painting and the corresponding restoration. The results show that the camphor wood samples are still significantly volatile and harmful to both metal and paper. This work would be meaningful to museum curators and conservators as a reference for making correct judgments when camphor wood is included in the potential material list.
The influence of initial imperfection on ultimate bearing capacity of cylindrical shells with continuous openings
Authors: Yu Banhai , Leng Wenjun , Liu Yong
Published: August 2023

Four kinds of initial imperfections were analyzed to obtain their influence on ultimate bearing capacity of cylindrical shells with continuous openings. The model was created in the finite element program. After the calculation of the nonlinear ultimate bearing capacity of cylindrical shells with continuous openings considering different kinds of initial imperfection and their amplitudes, the failure mode of the structure was studied and the buckling pressure was achieved. Compared with FEM and experimental results, it is proved that the numerical method used in this paper is reliable and could accurately forecast the ultimate bearing capacity of cylindrical shell with continuous openings.
Study on the seismic model of a special shelf structure
Authors: Li Shitu , Wu Tingwei , Bai Yujie , Jia Xiangyu
Published: August 2023

In this paper, the shelf structure is discretized, reduced in order, examined, and studied for seismic response by using the concentrated mass method, Lagrange method, transfer function method, and fourth-order Runge-Kutta method based on MATLAB numerical calculation. A simplified model of special equipment including supporting frame structure is proposed, and the calculation methods of equivalent mass, stiffness, and damping of supporting frame structure are given. In addition, the seismic response time-history curve of each position of the shelf structure is quickly obtained by using the lumped mass method in this paper. The conclusion is that the seismic response of the upper floor is greater than that of the lower floor, and the seismic response of the middle position of the same floor is greater than that of both sides. This paper provides a research foundation for the follow-up work. Research in this paper verifies the rationality of simplifying the complex dynamic model of the shelf structure continuum into a simple basic model, which provides a simplified model with a high fitting for the follow-up rub-impact analysis and research, and greatly improves the calculation efficiency.
Large-area WS2 Deposited on Sapphire and Its In-Plane Raman and PL Spectral Distributions
Authors: Wei Xiaoyu , Tang Zijun , Liu Chenxu , Zhu Huili , Zhou Changjie
Published: August 2023

Large-area and high-quality WS2 monolayer has been fabricated on the Al2O3 substrate. Three typical WS2 configurations were adopted to examine the in-plane spectral properties. For the triangle WS2 monolayer, the PL light region exhibits a large peak wavelength and could be deduced to be the relaxation of the compressed strain of the WS2 monolayer and the low defect density. For triangle WS2 monolayer with multilayer WS2 on center, combining the peak intensity and position results of PL and Raman spectra, the line traces near the side of the center triangle can be demonstrated to be the defects or dislocations due to the exist of the central multilayer WS2. For large-area WS2 monolayer with crystal domain, PL area integrated mapping shows a uniform light region across the whole surface, except the existing dark crystal domain boundary. The dark line traces could be attributed to compressed strain in the WS2 monolayer due to the formation of the WS2/Al2O3 hybrid structure. The in-plane PL and Raman spectra and mapping exhibited in this work reveal the distribution of stress and defects in this system and further clarify the effects of stress and defects on the optoelectronic properties of WS2 monolayer on Al2O3.
Propagation and attenuation of stress waves in heterogeneous elastic rods
Authors: Xie Suteng , Ru Yan
Published: August 2023

In this paper, the propagation and attenuation of stress waves induced by an integrable external load in an elastic rod with multiple inclusions are investigated. The traveling wave method is suggested for obtaining the reflection coefficient, transmission coefficient, and attenuation coefficient of the wave propagating from one media to another. Furthermore, the effects of wavelength and the size of inclusion on elastic wave propagation are calculated by the finite element method. The results show that the theoretical solution is fitted well with the finite element numerical results. The attenuation coefficient is influenced by material parameters, wavelength, and the number of inclusions. The smaller wavelength or more inclusions will incur the more obvious attenuation phenomenon. Moreover, the reflection coefficient and transmission coefficient are affected by the acoustic impedance ratio of the matrix and the inclusion. The results of this paper can be served as the theoretical basis for the study of wave propagation in heterogeneous materials.
Suppression of axial vibration of satellite antennas using the self-resetting frictional damper
Authors: Zhang Yunfei , Wang Min , Gao Xiangsheng , Gao Peng , Wang Guicheng , Che Changjia
Published: August 2023

In order to solve the problems of low-profile accuracy and poor control stability of the satellite antenna due to axial coupling vibration, in this paper, a self-resetting friction damper is proposed to suppress axial vibration. Firstly, a self-resetting friction damper, with a lightweight, wide frequency band, and high energy consumption, is designed. The principle of dry friction energy loss of metal rubber (MR) and the effect of self-resetting of shape memory alloy (SMA) are used. Secondly, the vibration reduction mechanism model of the self-resetting friction damper is established, and the principle of damping energy dissipation is analysed. Finally, sinusoidal excitation tests of the components of the satellite antennas with self-resetting friction dampers are carried out. The axial vibration loss factor of the components of the satellite antenna with the self-resetting friction damper is calculated, and the vibration resistance performance of the damper is verified. Theoretical analysis and experimental results show that the self-resetting friction damper has a significant effect on suppressing the axial vibration of the components of the satellite antenna. It is feasible to install a self-resetting friction damper in the components of the satellite antenna to suppress the axial vibration.
The contact condition of viscoelastic contact problems
Authors: Wang Fansheng
Published: August 2023

Three contact states in the viscoelastic contact deformation area between the rigid cylinder and the viscoelastic foundation are discussed based on various material mechanical properties between the rigid and the viscoelastic materials. On this basis, the relationship model between the node displacements and the node stresses in the boundary contact area is established, and the corresponding numerical analytical algorithms are used to simulate the viscoelastic contact deformation. Meanwhile, an example is given to simulate the contact deformation of the conveyor belt.
Abnormal Vibration Test and Cause Analysis of Bogie Brake Test Stand
Authors: Xue Mingchen , Wang Ruiqi
Published: August 2023

In this paper, the abnormal vibration of the bogie brake test stand during its operation is tested and analyzed. The vibration test and modal test were carried out for the test stand, and the radial runout test was carried out for the wheels of the bogie and the rollers of the test stand. By analyzing the results of the stability test, modal test, and Fourier transform method, the time-frequency spectrum of the bearing pedestal is obtained. The degree of the wheel polygon is obtained by analyzing the wheel out of roundness through the radial runout test results. The comprehensive comparison test results show that the coupling between the polygonal frequency of the wheel and the modal frequency of the bearing pedestal of the test stand leads to vibration amplification, which is also the main reason for abnormal vibration. Finally, some suggestions are put forward to improve the abnormal vibration.
Microstructure characterization and crystal plastic finite element simulation of additive manufacturing 316 L stainless steel
Authors: Huang Ziyang , Zeng Guowei
Published: August 2023

Due to the layer-by-layer molding mode of additive manufacturing (AM) technology, the mechanical properties of additive manufacturing structural parts are very different from those of traditional structural parts. The macroscopic mechanical properties of additive structural parts show obvious anisotropy; thus, the macroscopic model is not suitable to describe the effect of material microstructure (grain distribution, initial grain orientation, etc.) on the macroscopic mechanical behavior. Setting up a simplified structure microstructure of representative volume element (RVE), and the mechanical behavior response of AM 316 L stainless steel is simulated based on the finite element method for crystal plasticity. While uniaxial tension was regarded as a typical loading, the effect of microstructure on macroscopic mechanical properties is analyzed in combination with grain distribution and grain orientation. The results show that the numerical model not only reflects the impact of microstructure on macroscopic mechanical behavior but also suggests theoretical advice for practical production.
Evaluation of Carbon Reduction Potential and Economic Performance of Photovoltaic Charging System for Campus Electric Bicycles
Authors: Pan Jinjun , Xia Peng , Ma Xiang
Published: August 2023

This study considers the roof characteristics of different types of buildings in the Yuntang campus of Changsha University of Science and Technology, and evaluates the overall potential for photovoltaic power generation and carbon reduction performance of the campus by simulating the roof solar radiation at multiple time scales. In addition, a photovoltaic charging system for electric bicycles suitable for the campus is proposed based on the usage of electric bicycle charging stations on campus. The Monte Carlo method is used to simulate the hourly probability distribution of the charging load, and the capacity of the photovoltaic charging system is optimized by integrating the simulated solar radiation, outdoor temperature and other data, in order to strengthen the relationship between electricity demand and energy supply of the campus.
Electrochemical Copolymerization of Poly (MET-EDOT) with Enhanced Cyclic Stability
Authors: Zhang Hangchuan
Published: August 2023

To enlarge the electrochromic cyclic lifetime of poly (3-methtylthiophene) (PMET), the EDOT was copolymerized with the P3MT by electrochemical polymerization. The constant potential of 2.2 V was applied to the copolymer film growth in the electrolyte with 0.001 M EDOT and 0.1 M MET. The copolymer was achieved through the characteristics of the FT-IR and Raman analysis. The PMET-EDOT retained the vivid EC color from the PMET and the long cyclic stability from the PEDOT. The transmittance contrast of PMET-EDOT only decayed 1.5% after 1000 cycles. During the few components of EDOT in the copolymer, it seems similar that the transmittance spectrum and variation between the PMET-EDOT and PMET.
The study on the conductivity of TCNQ-modified 2D conjugated metal sulfur-dilute nanosheets
Authors: Sun Cuicui , Wang Wenchao , Lu Minghui , Zhang Mingdong , Wang Jiacun , Hao Ruichao , Wang Yaqi
Published: August 2023

Metal-organic frame materials are an important classification of new materials in metal-organic materials, and it is also the most popular area of research. Since the constituent bonds of the metal-organic framework are that the metal ions are connected to the redox-inert organic ligand, the conductivity of the MOF skeleton is not very good. There are many ways to improve the electrical conductivity of MOF skeletons, such as changing the variety of metal atoms and organic skeletons or introducing objects to modify the molecules. The way selected in this article to enhance the conductivity of the 2D conjugated metal sulfur-dilute MOF skeleton is to introduce the object-modified molecule TCNQ into the gap of the MOF material to enhance the conductivity of the material. This paper explores the conductivity of this material. After a series of calculations, the conductivity of 2D conjugated metal sulfur-dilute MOF modified by TCNQ was significantly improved.
The Anomalous Reflection and Refraction of Metasurface in the View of Solar Concentrators
Authors: Jin Qiyuan , He Jingwen , Wang Zhifeng , Guo Minghuan
Published: August 2023

Solar thermal power generation integrates photothermal conversion power generation and low-cost, large-scale heat storage, which is the primary support for constructing a green power system with new energy as the main body. The concentrating system is a critical component of solar thermal power plants. However, traditional concentrators are bulky and require complex solar tracking systems, limiting the reduction of solar thermal power costs. The metasurface can freely regulate electromagnetic waves and can be used in the field of solar concentrators, making it suitable for developing lightweight, low-cost, tracking-free solar concentrators and being a transformative technological solution in the energy field. Considering that the solar position varies with respect to a fixed planar metasurface concentrator, in this paper, we investigate the anomalous reflection and refraction phenomenon on the metasurface when the incident plane is not parallel to the direction of the static phase gradient of the metasurface. Utilizing vector equation derivation, Matlab calculation, and full-wave simulation based on the Finite difference-time domain (FDTD) method, all found the new property of the metasurface: its refracted ray, reflected ray, and normal are in the same plane, which is called the exit plane, and is at a certain angle to the incident plane.
Controllable Preparation and Size-Dependent SERS Performance of 35–410 nm Quasi-spherical Au NPs
Authors: Zhang Peina , Liu Tao , Zheng Jingxuan , Zhang Zhichao , Zuo Mengjiao
Published: August 2023

Uniform Au NPs with definite but different sizes will serve as a perfect model for studying the influence of NP size on surface-enhanced Raman scattering (SERS) performance. In this study, using tri-hydroxymethyl aminomethane (Tris-base) as a stabilizer and FeCl2 as a reducing agent, Au NPs with the size of 110–410 nm were prepared by a one-step method by simply changing the amount of FeCl2. In the preparation of small particle size Au NPs, sodium citrate was introduced as an auxiliary stabilizer, and 35–85 nm Au NPs were prepared in one step. In addition, the synthetic Au NPs of different sizes were loaded onto the glass substrate and 4-MOTP was used as the probe molecule to monitor their SERS properties. The results showed that the SERS activity results showed a “volcanic shape” with the change of nanoparticle size at a fixed excitation wavelength. The 160 nm Au NPs have the best SERS performance when the excitation wavelength is 633 nm.
Polysaccharide-modified conductive hydrogel for flexible electronic devices
Authors: Ji Chongkai , Li Lijie , Nie Yulin , Ping Rang , Peng Jiong , Li Xin
Published: August 2023

In recent years, conductive hydrogels, as an ideal flexible material, have quite broad application prospects in various flexible electronics fields, such as flexible supercapacitors, flexible batteries, and flexible sensors. However, mechanical stress such as stretching, fracture, and compression will affect the performance of conductive hydrogel during the application, which limits its further application. Polysaccharides, such as cellulose and chitosan, are widely distributed and easy-to-obtain biological macromolecules, which contain a large number of polar functional groups (carboxyl, amino, etc.), which can be formed with polymer hydrogel molecular chains, thereby improving the performance of the hydrogel. Herein, we prepared a kind of conductive hydrogel with high toughness, high conductivity, and self-adhesion by introducing carboxymethyl chitosan and maltose to induce a dynamic Schiff base reaction in the hydrogel. It is conceived that this study proposed a potential approach for the progress of conductive hydrogels in various flexible electronics fields.