bluuebunny/crossref_metadata_2025 huggingface dataset:
Final report of CCQM-P225a and b, international comparison on carbon dioxide in air and nitrogen at ambient levels (350 μmol/mol to 800 μmol/mol)
Authors: Viallon J , Choteau T , Moussay P , Wielgosz R I , Veen A M H van der , Bi Z , Crotwell A , Hall B , Webber E Mussel , Hill−Pearce R , Brewer P , Worton D , Macé T , Sutour C
Published: November 2023

Main text

The pilot studies CCQM-P225a and b aimed at validating the performance of the pVT−CO2 manometric reference facility maintained at the BIPM as a reference for the planned ongoing comparisons BIPM.QM-K2a and b for CO2 in air and nitrogen standards, respectively, over the range 350 μmol mol−1 to 800 μmol mol−1. The planned launch date of the BIPM.QM-K2a and b comparisons is 2024 and will enable NMIs and DIs to have access to on-demand comparisons for their CO2 in air and nitrogen standards over the range 350 μmol mol−1 to 800 μmol mol−1.

The pilot studies supplemented the validation activities on the BIPM reference facility already reported in CCQM-P188, and ongoing validation studies against NIST, NOAA and VSL gas standards. A description of the BIPM facility performance will be submitted for publication in a peer-reviewed journal in 2023, with a full uncertainty analysis showing that it can operate with a standard uncertainty of 0.1 μmol mol−1 over the amount fraction range of the comparison (Viallon et al 2023b).

The comparison was organised using a sufficient number of independent standards, to demonstrate the performance of the BIPM system, whilst limiting the duration of the pilot study, allowing the key comparison to start as planned in 2024. Following discussions at the 44th GAWG meeting it was decided that comparisons with 3 independent standards at 3 nominal amount fraction values (380, 480 and 800 μmol mol−1) in the two matrices (air and nitrogen) would be sufficient.

Results presented in this report show a good agreement between values assigned by participants and those measured at the BIPM, over the entire range of the comparison and for both matrices (air and nitrogen). The BIPM pVT−CO2 facility is ready to act as reference facility for the ongoing key comparison BIPM.QM−K2.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Bounding Free Energy Difference with Flow Matching
Authors: Zhao 赵 Lu 辂 , Wang 王 Lei 磊
Published: November 2023

We introduce a method for computing the Helmholtz free energy using the flow matching technique. Unlike previous work that utilized flow-based models for variational free energy calculations, this method provides bounds for free energy estimation based on targeted free energy perturbation by performing calculations on samples from both ends of the mapping. We demonstrate applications of the present method by estimating the free energy of a classical Coulomb gas in a harmonic trap.
PbMg 1/3
Nb
2/3
O3 dielectric aging in the freezing temperature region
Authors: Vakhrushev S B , Koroleva E Yu , Molokov A Yu , Vakulenko A F , Filimonov A V , Rudskoy A I
Published: November 2023

Aging of the relaxors and PbMg

1

/

3

Nb

2

/

3

O3 in particular was extensively studied in last two decades. Most of the results were related to the low temperature glass-like region. No systematic data around the freezing temperatures were reported. To cover this still missing information we have studied the evolution of the dielectric spectra in the broad frequency region from 10−1 Hz to 106 Hz both below and above the freezing temperature

T
f

≈

240 K. Below freezing temperature the existence of the earlier reported waiting time–frequency scaling at frequencies below ≈50 Hz is confirmed. At higher frequencies this deviation from the scaling is observed that can be tentatively attributed to the complexity of the relaxing entities. Above Tf
aging is observed only in the restricted frequency interval below the maximum of the dielectric loss spectrum. The observed effect can be attributed to the hardening and narrowing of the dielectric loss spectra and decreasing of the dielectric strength with time. The explanation is proposed based on the concept of the creation of the degenerate polar nanoregions covering several chemically ordered regions (COR) (multi PNRs—MPNRs). These MPNRs are large compare to the PNRs located at the single CORs and some of them may become frozen resulting in the described spectra changes.
Latest innovations in the field of condition-based maintenance of rotatory machinery: a review
Authors: Kumar Anil , Gandhi C P , Tang Hesheng , Sun Weifang , Xiang Jiawei
Published: November 2023

Health monitoring in rotatory machinery is a process of developing a mechanism to determine its state of deterioration. It involves analysing the presence of damage, locating the fault, determining the severity of the problem, and calculating the amount of time that the machine can still be used effectively by making use of signal processing methods. The journey started to repair when the machine fails and progressed to the modern era, which involves the use of advanced sensors to capture data and conduct on-line signal processing methods to extract relevant features. By seamlessly integrating advanced smart sensing, data collection, and intelligent algorithms, modern technologies have transformed the landscape of condition-based maintenance for rotary machinery, bridging the gap between fundamental understanding and practical engineering applications. In this review paper, first, the roadmap of the condition-based maintenance (CBM) journey for rotary machinery is briefly introduced. Then, CBM task techniques are reviewed in the context of manual identification of defects, applying artificial intelligence (AI) model to identify the defect in the rotary machinery, and AI to carry out defect prognosis and determine the remaining useful life. Finally, the challenges, and issues of signal processing methods to detect faults in rotary machinery, and remedies to overcome such challenges are deeply discussed and future research directions are identified to ensure safe operation for rotary machinery.
Research on wind field visualization based on UAV wind measurement method
Authors: Pu Ou , Yuan Boqiu , Li Zhengnong , Bao Terigen , Chen Zheng , Zhang Shibo , Yan Jin , Li Zhen
Published: November 2023

This study introduces an efficient and precise method for gathering atmospheric wind field data in specific regions, utilizing unmanned aerial vehicles (UAVs) equipped with anemometers. We conducted outdoor wind field measurements over complex terrains using a six-rotor UAV equipped with an ultrasonic anemometer. The results obtained include a vertical wind field profile at the center of the measured site, along with two planar wind field profiles at 20 m and 40 m heights. The analysis reveals a remarkably high fitting accuracy for the wind profile and turbulence intensity results obtained. Furthermore, the planar wind field data partially demonstrates the impact of terrain on the upper-level wind field within the surveyed area. Lastly, we established a three-dimensional wind field visualization approach using the data gathered through the UAV wind measurement method, implementing Kriging interpolation. This study’s outcomes offer novel insights and methodologies for local wind field measurement, micro-siting in wind farms, and the creation of visualized wind fields.
Effect of vacancy defects on anisotropic electronic transport behaviors of CoN4C2 based 2D devices: a first-principles study
Authors: Yang Wenhao , Chen Tong , Xie Luzhen , Yu Yang , Luo Cheng , Long Mengqiu
Published: November 2023

The strong anisotropic electronic transport properties of the single-atom-thick material CoN4C2 monolayer hold immense importance for the advancement of the electronics industry. Using density functional theory combined with non-equilibrium Green’s function systematically studied the electronic structural properties and anisotropic electronic transport properties of the CoN4C2 monolayer. The results show that Co, N, and C single-atom vacancy defects do not change the electronic properties of the CoN4C2 monolayer, which remains metallic. The pristine device and the devices composed of Co, N single-atom vacancy defects exhibit stronger electronic transport along the armchair direction than the zigzag direction, which exhibit strong anisotropy, and a negative differential resistance (NDR) effect can be observed. In contrast to the results mentioned above, the device with C single-atom vacancy defects only exhibits the NDR effect. Among them, the device with the N single-atom vacancy defect regime exhibits the strongest anisotropy, with an I
Z/I
A of up to 7.95. Moreover, based on the strongest anisotropy exhibited by N single-atom vacancy defects, we further studied the influence of different sites of the N-atom vacancy on the electronic transport properties of the devices. The results indicate that N-1, N-2, N-3, N-12, N-23, N-123, N-1234, and N-12345 model devices did not change the high anisotropy and NDR effect of the device, and among them the N-1234 exhibits the strongest anisotropy, the I
Z/I
A reaches 6.12. A significant NDR effect is also observed for the electronic transport along the armchair direction in these devices. However, the current gradually decreases as an increase of the number of N defects. These findings showcase the considerable potential for integration of the CoN4C2 monolayer in switching devices and NDR-based multifunctional nanodevices.
Enhancing β-Ga2O3-film ultraviolet detectors via RF magnetron sputtering with seed layer insertion on c-plane sapphire substrate
Authors: Wang Guodong , Wang Haohan , Chen Tingyu , Feng Yanji , Zeng Hua , Guo Lanlan , Liu Xiaolian , Yang Yingli
Published: November 2023

Gallium oxide (Ga2O3) possesses a band gap of approximately 4.9 eV, aligning its detection wavelength within the solar-blind region, making it an ideal semiconductor material for solar-blind photodetectors. This study aims to enhance the performance of Ga2O3 ultraviolet (UV) detectors by pre-depositing a Ga2O3 seed layer on a c-plane sapphire substrate. The x-ray diffraction and x-ray photoelectron spectroscopy analyses validated that the deposited films, following high-temperature annealing, comprised β-Ga2O3. Comparing samples with and without a 20 nm seed layer, it was found that the former exhibited fewer oxygen defects and substantially improved crystal quality. The incorporation of the seed layer led to the realization of detectors with remarkably low dark current (≤15.3 fA). Moreover, the photo-to-dark current ratio was enhanced by 30% (surpassing 1.3 × 104) and the response/recovery time reduced to 0.9 s/0.01 s, indicating faster performance. Furthermore, these detectors demonstrated higher responsivity (4.8 mA W−1), improved detectivity (2.49 × 1016 Jones), and excellent solar-blind characteristics. This study serves as a foundational stepping toward achieving high-quality β-Ga2O3 thin film and UV detector arrays.
A Monte Carlo study on the secondary neutron generation by oxygen ion beams for radiotherapy and its comparison to lighter ions
Authors: Geser Federico A , Stabilini Alberto , Christensen Jeppe B , Muñoz Iván D , Yukihara Eduardo G , Jäkel Oliver , Vedelago José
Published: November 2023

Objective.To study the secondary neutrons generated by primary oxygen beams for cancer treatment and compare the results to those from primary protons, helium, and carbon ions. This information can provide useful insight into the positioning of neutron detectors in phantom for future experimental dose assessments.Approach.Mono-energetic oxygen beams and spread-out Bragg peaks were simulated using the Monte Carlo particle transport codesFLUktuierende KAskade, tool for particle simulation, and Monte Carlo N-Particle, with energies within the therapeutic range. The energy and angular distribution of the secondary neutrons were quantified.Main results.The secondary neutron spectra generated by primary oxygen beams present the same qualitative trend as for other primary ions. The energy distributions resemble continuous spectra with one peak in the thermal/epithermal region, and one other peak in the fast/relativistic region, with the most probable energy ranging from 94 up to 277 MeV and maximum energies exceeding 500 MeV. The angular distribution of the secondary neutrons is mainly downstream-directed for the fast/relativistic energies, whereas the thermal/epithermal neutrons present a more isotropic propagation. When comparing the four different primary ions, there is a significant increase in the most probable energy as well as the number of secondary neutrons per primary particle when increasing the mass of the primaries.Significance.Most previous studies have only presented results of secondary neutrons generated by primary proton beams. In this work, secondary neutrons generated by primary oxygen beams are presented, and the obtained energy and angular spectra are added as supplementary material. Furthermore, a comparison of the secondary neutron generation by the different primary ions is given, which can be used as the starting point for future studies on treatment plan comparison and secondary neutron dose optimisation. The distal penumbra after the maximum dose deposition appears to be a suitable location for in-phantom dose assessments.
Feature detection of mineral zoning in spiral slope flow under complex conditions based on improved YOLOv5 algorithm
Authors: Keshun You , Huizhong Liu
Published: November 2023

In actual processing plants, the quality and efficiency of the traditional spiral slope flow concentrator still rely on workers to observe the changes in the mineral belt. However, in realistic complex working conditions, the formation of mineral separation zones is subject to large uncertainties, and coupled with the limited efforts, experience, and responsibility of workers, it becomes important to free up labour and improve the efficiency and profitability of the beneficiation plant. Therefore, to solve the problem of difficult detection of fuzzy small target mineral separation point features in real scenes, an improved YOLOv5-based algorithm is proposed. Firstly, the dataset quality is well improved by image enhancement and pre-processing techniques, after that an innovative CASM attention mechanism is added to the backbone of the YOLOv5 model, followed by a multi-scale feature output and prediction enhancement in the neck part of the model, and an optimized loss function is designed to optimize the whole feature learning process. The improved effect of the model and the specific detection performance were tested using real mine belt image datasets, the ablation experiment verified the comprehensive effectiveness of the proposed improved method and finally compared it with the existing high-level attention mechanism and target detection algorithms. The experimental results show that the improved YOLOv5 algorithm proposed in this study has the best overall detection performance carrying a MAP of 0.954, which is over 20% better than YOLOv5. It is worth mentioning that the improvement to achieve this performance only increases the parameter values by 0.8M and GFLOPs by 1.8, moreover, in terms of the inference speed, it also achieves a respectable 63 FPS, implying that the proposed improved method achieves a better balance between the performance enhancement and the computational complexity of the model, the overall detection results fully satisfy the industrial requirements.
The vortex light induced electric dipole and electric quadru-pole transition in Ca atom
Authors: Lu Zhenzhong , Liu Min , Feng Ce , Zhou Jiannan
Published: November 2023

The Laguerre–Gaussian beam induced electric transition model is presented. The major mechanism of angular momentum exchange between the light and the atomic system is discussed. The influence of the topological charge on the transition probability and selection rules is obtained. Our results show that the Ca(4s2 1S0–4s3d 1D2) electric quadrupole transition selection rules are sensitive to the sign of l, and the center of mass transition selection rules are governed by the topological charge l of the light. The electric dipole transition is possible in a field with topological charge l > 0, and the quadrupole transition is no longer forbidden. The overall transition probability difference between dipole transition and quadrupole transition can be decreased by the joint action of the light angular momentum exchange with the external and the internal motion.
On how fast ions enhance the regulation of drift wave turbulence by zonal flows
Authors: Choi G.J. , Diamond P.H. , Hahm T.S.
Published: November 2023

This paper presents a mechanism for enhanced regulation of drift wave turbulence by zonal flows in the presence of a fast ion population. It demonstrates that dilution effects due to the energetic particles (EPs) have a far-reaching impact on all aspects of the nonlinear dynamics. The modulational growth of zonal flow shear and the corresponding evolution of drift wave energy are calculated with dilution effects. The coupled zonal flow growth and drift wave energy equations are reduced to a predator–prey model. This is solved for the fixed points, which represents the various states of the system. Results display a strong dependence on dilution, which leads to greatly reduced levels of saturated turbulence and transport. Implications for the FIRE mode plasma of KSTAR are discussed in detail. This model is perhaps the simplest dynamical one which captures the beneficial effects of EPs on confinement.
Microstructure of phosphate conversion film formed on the surface of A36 steel prepared by micro-arc discharge plasma
Authors: Chen H L , Wu Y D , Yeah C C
Published: November 2023

Phosphate conversion film is an important surface protection film for steel. It mainly has the functions of corrosion resistance, wear resistance, plastic processing lubricity, etc., or as the basis of subsequent coating or painting. Phosphate treatment is traditionally used to form a Phosphate conversion film on the surface of steel. In this treatment method, a dilute solution of phosphoric acid and phosphate can be applied to the surface to be treated by spraying or soaking, so that it can react with the surface to form an insoluble phosphate film. This method is more difficult to control the thickness and microstructure of the formed film, and there are many pretreatment procedures. In response to future environmental policies, carbon neutrality and 2050 net zero carbon emissions must be met. In this study, the micro-arc discharge method was used from the surface pretreatment of A36 steel to the formation of the phosphoric acid film. The consistent method shortened the process steps and reduced the carbon emission of the process to comply with the environmental policy. The discharge voltage is 50 ∼ 200 V, the current is about 1.6 A, and the different process time and current are controlled, which to observe the microstructure of the phosphoric acid film and surface hardness. Possible reaction mechanisms for phosphate film formation will be discussed in this paper.
Study on the application of 3D printing to wooden furniture connectors
Authors: Chen C C , Yang W Z , Teng H M , Liao S S , Tsao C C
Published: November 2023

With the rapid development of high technology in the 21st century, the manufacturing industry cannot be exempted from it. In addition, 3D printing is a multi-layer manufacturing technology that has emerged in recent years, and it is gradually integrated into the manufacturing process of components in various industries, such as aerospace, medical, military, transportation and construction industries. However, the use of 3D printing to make wooden furniture connectors has gradually replaced the traditional way of connecting wooden furniture. Like other 3D printed products, the size of the connectors of 3D printed wooden furniture is also affected by its molding accuracy. In order to obtain the best precision 3D printed wooden furniture connectors, the experimental parameters of this study are designed by Taguchi experiment method, and the measurement is carried out by 3D scanner equipment. The research results show that when the experimental parameters are the nozzle temperature of 200 °C, the layer thickness of 0.1 mm, the filling degree of 20 %, and the extrusion speed of 50 mm/s outside and 100 mm/s inside, the printed 3D wooden furniture connectors have the best accuracy.
The effect of carrier locking position on the dynamic characteristics of gapless miniature linear guideway
Authors: Chen C M , Chang H L , Chien C Y , Tsui C W
Published: November 2023

The analysis of the load position of the miniature linear guideway is very important for the dynamic friction characteristics of the linear motion equipment. In this paper, a miniature guideway dynamic friction coefficient tester will be designed. And the effect of load position, movement speed, and load on the friction force of linear guideway will be investigated according to the gapless. The experimental results show that the friction force will be dependent on the load position, load, and movement speed. Among them, the lowest frictional load position can be obtained at any speed of movement and load condition, which occurs at the central load position. The main reason for this is that the effect of the moment is minimum. On the same load position and movement speed, then load is proportional to friction. In the case of fixed load and load position, the effect of velocity on friction is positively correlated in the longitudinal offset position. The frictional force is aggravated by the unevenly distributed pressure on the inner ball due to the moment generated by the slider. At the same time, by observing the loading and the inclination angle of the carrier in the experiment with the laser displacement meter, it can be found that the inclination angle also tends to increase when the load increases.
FEM simulation on forming vacuum hexagon socket screws using tube workpiece
Authors: Teng H Y , Tzou G Y , Lu C , Huang G M
Published: November 2023

This study proposes a new forming design concept to produce vacuum hexagon socket screws using tube workpiece, and uses the finite element simulation software DEFORM-3D to simulate the multi-pass forming process of vacuum hexagon socket screws. The simulated material is SUS-304 stainless steel, and the frictional conditions are assumed to be constant shear friction, the die is assumed to be a rigid body. In the past, the traditional vacuum hexagon socket screw manufacturing process used a multi-pass process to manufacture a standard screw using a solid workpiece (wire rod), and then drilling an air channel in the core of the screw. This process not only wastes time, but also needs to increase the processing cost. In this study, the time and cost of drilling the air channel can be reduced by forming the vacuum hexagon socket head screw through the hollow tube. The finite element simulation results confirm that this design is a feasible method. The pass schedule can be reduced from 6 stages to 3 stages, the maximum effective stress decreased by 28.13%, and the total forming force decreased by 57.66%. The research results can be provided to relevant industry as the reference.
Preparation of modified expanded graphite and research on emulsified oil adsorption performance
Authors: Yu Qian , Kan Kan , Sun Tianshu , Zhang Xiaochen
Published: November 2023

Modified expanded graphite was prepared from expanded graphite and characterized by FT-IR, XRD and SEM. The results showed that the modified linear alkyl was successfully grafted onto the surface of expanded graphite, and the crystal structure and overall morphology did not change significantly after modification. Expanded graphite and modified expanded graphite adsorption columns were prepared, the adsorption experiment of emulsified oil was carried out. When the initial concentration of emulsion oil solution is 100 mg·L−1, the filling density is 3.5 g·L−1, and the flow rate is 3 L·h−1, the emulsion oil concentration decreases to 93 mg·L−1 and 6.5 mg·L−1, respectively, after adsorption by expanded graphite and modified expanded graphite, indicating that the adsorption performance of modified expanded graphite on emulsified oil is obviously improved. The saturated adsorbed modified expanded graphite was recycled by vacuum filtration. The results show that the modified expanded graphite still has good adsorption performance for emulsified oil after 1-3 times of regeneration, and can be used as adsorption material or recycled into sealing material.
Calcined and Hydrated Shell Powder with Layered Porous Structures for Food Sterilization and Pesticide Residue Removal
Authors: Liu Y S , Tang K X , Liao Y T , Huang R R , Zhu Y , Chen Z , Chen Y , Lin L
Published: November 2023

Shell powder, a natural source product with excellent adsorption and antibacterial properties, has exhibited a broad application prospect in daily life. Herein, low-temperature calcined shell powder (LCSP) and high-temperature calcined and hydrated shell powder (HCSP) were prepared using shells as raw materials in different calcination processes. The surface structures and the chemical compositions were analyzed and the specific surface areas and pore size distributions were measured. The LCSP and HCSP reserved the unique layered porous structures of the shell. The main composition of LCSP is CaCO3, which also contains a small number of organisms. The main composition of HCSP is Ca (OH)2, which also contains CaO and a small amount of CaCO3. According to the better adsorption characteristic of the HCSP, the antibacterial activities and the removal abilities of pesticide residues of HCSP were systematically studied. The results indicated that HCSP exhibited excellent antibacterial activity (> 99.99%) and high efficiency in removing common pesticide residues (> 90%).
Microstructure and Properties of TiCp/GH3536 prepared by Selective Laser Melting
Authors: Li Yan , Liu Jiawei , Song Meihui , Zhang Yu , Li Yanchun , Zhang Xiaochen
Published: November 2023

In this paper, TiCp/GH3536 composites were prepared by selective laser melting technology. The effects of volume energy density (VED) on the microstructure, densification, mechanical properties and thermophysical properties of TiCp/GH3536 composites were studied. The results show that the pores and nano TiC clusters in TiCp/GH3536 composites gradually disappear with the increase of VED. The interface between TiC ceramic phase and GH3536 matrix was well bonded, which was a non coherent interface, and there was no interface reactant. The optimal VED of SLM is 96.3 J/mm3, and the specific laser power, scanning rate, scanning spacing and powder layer thickness were 260W, 900 mm/s, 0.1mm and 0.03mm, respectively. The highest density of the composite is 99.96%; The maximum tensile strength and yield strength were 1137.2MPa and 900.6MPa, respectively.
Study on the microstructure and properties of copper/graphite composites with two-step method and copper-modified graphite
Authors: Ding Yi , Gao Jianfeng , Han Yu , Zhou MingYu , Wang HaiTian , Zhang Congrui , Liu Jinping , Wang YueChen , Ding Zhiyong , Wang Jing , Zhu ZhiXiang
Published: November 2023

In this experiment, copper was coated on the surface of graphite by chemical process. Besides, the microstructure and crystal structure of copper-coated graphite were characterized by SEM and XRD. Copper-plated C/Cu composite was prepared by SPS sintering technique of powder mixture by two-step method. In order to test the dispersion state of graphite in the composites and the phenomenon of interfacial dispersion, the effect of graphite content on the properties of copper-coated C/Cu composites was also an important point. Therefore, the microscopic characterization and performance test were carried out. The results show that magnetic stirring and high-energy ball milling ensure the uniformity of copper-coated graphite in copper matrix, and conducted structural grain refining. The grain size of copper, and the properties of composite materials decreased with the increase of graphite content, such as relative density, conductivity and hardness. However, the further increase of graphite content leads to excessive grain size, the relatively long time of ball milling makes the fine grain become larger after sintering. When the graphite content is 1.0wt.%, the relative density, conductivity and hardness are 99.91%, 92.1%IACS and 67.7 HV, respectively. It is proved that copper-coated graphite and two-step powder mixing play an important role on improving the properties of the composites.
Long-life Inorganic Electrochromic Device Based on WO3 and PB Films with Fast Switching Respond
Authors: Wei Y X , Li J Y , Liu W M , Yan Y
Published: November 2023

Complementary electrochromic devices were fabricated by using tungsten trioxide (WO3) film as working electrode, Prussian blue (PB) film as counter electrode and 0.1 M lithium perchlorate in propylene carbonate as electrolyte. The XRD result presents that WO3 and PB films are amorphous, which is favourable for a fast ion intercalation-deintercalation process. The device was tested under potentiostatic control using ±1.3 V steps, and changed its color between blue and colorless. It has a fast-switching respond (about 1.5 s for colouring and 2 s for bleaching) and could withstand 100,000 cycles with little change in its optical contrast.
Research on the manufactured Technology of High-precision Load Connecting Frame Structure with Special-shaped Variable Shaped Cross-section
Authors: Xu Ting , Wu Haisheng , Sheng Chao , Fang Jin , Guo Xiaoyong , He Cheng , Wei Yuxuan
Published: November 2023

Aiming at the research and development technology of high-precision load connecting frame structure with special-shaped variable cross-section reinforced by internal cross bars, the two-step weaving and stitching fiber preform forming process scheme and the general RTM product forming process scheme of load connecting frame are discussed by using the comparison method; The virtual simulation of RTM glue injection process is studied by using ESI Group software, and the results show that the completion time of the glue injection process with four sprues is about 29.4% of that of the glue injection process with only one sprue, which guides the design of RTM molding design; The key process of product manufacturing, such as the glue injection and curing process of the product and the quality control process during the technological process, are analyzed, and the performance of the final product is evaluated. Through the research on the manufacturing process, we have overcomed the major constraints on several molding technologies, such as the two-step fiber preform molding technology of weaving and stitching, the RTM molding design and processing technology of complex and special-shaped composite products, the split molding technology, and combination finishing processing technology after secondary bonding. The results prove that the formed products have better forming quality, dimensional accuracy and thermal cycle dimensional stability. The nondestructive testing results of composite parts show that the internal structure of the product is good. The fiber volume fraction is controlled at (55 ± 3)%, the flatness of the important surface of the product is 0.05 mm and 0.03mm respectively, and the dimensional accuracy of the important interface is controlled within ± 0.02 mm. The dimensional stability after the thermal cycle test is good, and all indicators of the product meet the user’s requirements, which achieved expected goals. The success on the manufacturing of these products provides a technical basis for the design and manufacture of high-precision and high stiffness composite structures for deep space exploration and manned spaceflight.
Preparation and Properties of Graphene/ODA-PMDA-NTADA Copolyimide Nanocomposites Based onKH550-modification
Authors: Li Quantao , Zhu Pengcheng , Zhu Yanjin , Wang JianFei , Chen Wenqiu , Xu Zushun
Published: November 2023

In this study, KH550-modified graphene/ODA-PMDA-NTADA copolyimide nanocomposites were successfully made in an organic medium using KH-550 chemically modified reduced graphene oxide (rGO-NH2) as a multi-functional comonomer combinied with commercially available ODA, PMDA, and NTADA monomers, and their dispersive, morphological, thermal, viscous, conductive properties were investigated. Compared to pure PI, the dispersion compatibility, thermal characteristics and electrical conductivity of the produced nanocomposites were improved significantly. The improved rGO/PI nanocomposites showed more than 20 °C and 10 °C increase of Td5% and Td10% values respectively. This research demonstrates a facile and efficient method for creating homogeneous and multi-functional PI-based engineering materials and advanced functional materials.
Yellow YAG-Ag/Al2O3 film applied to blue laser illumination
Authors: Wen Haiyang , Zhou Tianliang , Xie Rong-Jun
Published: November 2023

The most popular light-emitting component for laser illumination right now is phosphor in glass (PiG), however its major weakness is the poor heat conductivity. In this research, the yellow YAG:Ce phosphor and Ag paste were co-fired on an Al2O3 substrate using the blade-coating approach to create a PiM (phosphor in metal) film. Due to the ultra-high thermal conductivity of Ag, the highest blue laser power density that YAG-Ag PiM can achieve is 9.2 W·mm−2, and the maximal luminous flux, lumen efficiency and CCT (correlated color temperature) are 620 lm, 172 lm·W−1 and 6244 K, respectively.
Failure Analysis of Corrosion and Fracture of P110 Tubing in a Development Well
Authors: Han Yan , Ren Hong , Zhang Wenbin , Fu Anqing , Ma Qingwei
Published: November 2023

In this paper, a fractured and corroded tubing string was analyzed through macroscopic observation, chemical composition analysis, metallographic and mechanical test. The corrosion products were studied by SEM, EDS, and XRD method. The results showed that the corrosion of tubing in this well was caused by CO2 corrosion, the well contains CO2 medium and increasing water cut in the late stage of development were the main reasons of serious corrosion, the scaling on the tubing wall aggravated the corrosion. Finally, some suggestions were proposed for avoiding or slowdown this kind of corrosion failures.
Above-room-temperature ferromagnetism in a layered CrIr2Sn10 crystal
Authors: Sun Xuzhou , Yang Ke , Fang Yuqiang , Wu Hua , Huang Fuqiang
Published: November 2023

Layered ferromagnetic (FM) materials are significant for nano-spintronic devices, however, low transition temperature and air instability remain major challenges for layered FM compounds. Herein, we have synthesized layered crystals CrIr2Sn10 with FM transition below 315 K. The ratio of the magnetization between in-plane and out-of-plane is 41. Moreover, the magnetism of CrIr2Sn10 is derived from the highly spin-polarized Cr atoms. CrIr2Sn10 will be a promising platform for 2D magnetism and spintronic devices.
Higher-order obstructed atomic insulator phase in pentagonal monolayer PdSe2
Authors: Nuñez Victor , Bravo Sergio , Correa J D , Chico Leonor , Pacheco M
Published: November 2023

We investigate a pentagonal monolayer of palladium diselenide, a stable two-dimensional system, as a material realization of a crystalline phase with nontrivial topological electronic properties. We find that its electronic structure involves an atomic obstructed insulator related to higher-order topology, which is a consequence of the selenium-selenium bond dimerization along with inversion and time-reversal symmetry). By means of first-principles calculations and the analysis of symmetry indicators and topological invariants, we also characterize the electronic corner states associated with the atomic obstruction and compute the corresponding corner charge for a finite geometry, which is found to be not quantized but still inversion-protected. Applying tensile strain to the finite geometry we verify the robustness of the corner states and also achieve a strain-controlled variation of the corner charge magnitude.
EEG-fest: few-shot based attention network for driver's drowsiness estimation with EEG signals
Authors: Ding Ning , Zhang Ce , Eskandarian Azim
Published: November 2023

The leading factor behind most vehicular accidents is the driver’s inattentiveness. To accurately determine driver’s drowsiness, Electroencephalography (EEG) has been proven to be a reliable and effective method. Even though previous studies have developed accurate driver’s drowsiness detection algorithms, certain challenges still persist, such as (a) limited training sample sizes, (b) detecting anomalous signals, and (c) achieving subject-independent classification. In this paper we propose a novel solution, names as EEG-Fest, which is a generalized few-shot model aimed at addressing the aforementioned limitations. The EEG-Fest has the ability to (a) classify a query sample’s level of drowsiness with only a few support sample inputs (b) identify whether a query sample is anomalous signals or not, and (c) perform subject-independent classification. During the evaluation, our proposed EEG-Fest algorithm demonstrates better performance compared to other two conventional EEG algorithms in cross-subject validation.
Tensile properties and fracture behaviors of electron-beam welded Ti6242 titanium alloy joints
Authors: Fang Xu , Jing Wen , Xiufeng Han , Jianfeng Zhang
Published: November 2023

The microstructure, tensile properties and fracture behaviors of electron-beam welded Ti6242 titanium alloy joints were systematically investigated. The as-received alloy exhibited a typical duplex microstructure consisting of equiaxed primary α phase and laminated secondary α phase/β phase. The high cooling rate during welding resulted in substantially microstructure evolution in the fusion zone (FZ) of the joints, leading to the formation of large columnar β grains with embedded acicular α′ martensitic phase platelets. The influences of such microstructure variations on the mechanical properties and fracture behaviors at different temperatures were analyzed and discussed. In principle, the hard-yet-brittle α′ martensitic phase induced significantly strengthening of the FZ. As a result, for the un-notched specimens, the plastic deformation was concentrated to the soft base material with subsequent ductile fracture via micro-void coalescence mechanism. But for the notched specimen, in which the notch located just within the FR, cracks initiated and proceeded along the FR in a brittle manner.
Law Without the State
Authors: Levinson Daryl J
Published: November 2023

An effective system of law must be able to authoritatively specify what the law is, and then get its subjects to follow it. Skeptics of international law have long questioned its ability to meet this standard, wondering, for instance, why a global superpower like the United States would bow to a rule of international law that disserved its interests, rather than changing, disregarding, or interpreting it away. Constitutionalists have paid less attention to these kinds of questions than their internationalist counterparts, but they have equal reason to wonder why, for instance, a president of the United States would choose to abide by constitutional limitations rather than dismissing them as merely “parchment barriers.” This chapter describes the common challenge of constitutional and international law in achieving legal settlement and compliance in the absence of a crown-wearing, sword-wielding Leviathan standing above.
Law Versus Sovereignty
Authors: Levinson Daryl J
Published: November 2023

Sovereignty, as Hobbes conceived it, denied the existence of any higher power standing over the state—including the power of law, international or constitutional. Even as these systems of law for states have taken hold, they have been forced to wrestle with ongoing Hobbesian doubts. As recent waves of populist and nationalist resistance to globalism illustrate, international law is too easily cast as an illegitimate threat to state sovereignty. While constitutional self-government is sometimes held up as the contrasting ideal, sovereignty is no less a problem for constitutionalism, demanding an explanation for why legal limitations on democratic self-governance serve not as constraints on popular sovereignty but as sovereignty’s authentic expression. This chapter presents the parallel struggles of international and constitutional law to come to grips with sovereignty, while suggesting that the “artificial man” of Leviathan has made Hobbesian sovereignty an artificial problem for regimes of law governing the state.
Balancing Power
Authors: Levinson Daryl J
Published: November 2023

Another approach to controlling state power is to “balance” it. From Hobbes to Henry Kissinger, international relations realists have looked to the balance of power among rivalrous states as the best hope of keeping them mutually in check. Constitutionalists since Madison have attempted to recreate the realist strategy within the state, relying on the competing “ambitions” of the different branches of government to generate a stable equilibrium of checks and balances. As this chapter explains, however, the constitutional version of power-balancing is doubly misguided. One problem, long recognized by internationalists, is that the realist premise of perpetual competition among power-seeking Leviathans often fails, for predictable reasons, to match the actual behavior of states and governments. But the more fundamental problem is that balancing power at the level of government bodies does nothing to protect the people and groups in society who are actually vulnerable to domination and oppression. Constitutionally balanced power is no bar to tyranny.
New Leviathans
Authors: Levinson Daryl J
Published: November 2023

After a triumphant run of half a millennium since Hobbes, the state appears to be weakening, if not withering away. Increasingly usurping the state’s functions are a proliferation of international, regional, and nongovernmental organizations engaged in “global governance.” At the same time, the power of states to control their economies and societies has been challenged and rivaled by Big Tech and other multinational corporations, which have increasingly come to resemble privatized, nonterritorial governments. This final chapter explores what might be different in a world in which states have ceded power to these new Leviathans, global and corporate. As far as the design of legal regimes goes, the answer may be, surprisingly little. Even if the Hobbesian state is on the road to retirement, Law for Leviathan is likely to live on.
Particle Physics: A Very Short Introduction
Authors: Close Frank
Published: November 2023

Particle Physics: A Very Short Introduction takes a journey into the atom and presents an overview of the fundamental particles and forces that make up the universe. The VSI discusses the features and functions of particles such as quarks, electrons, and neutrinos, and of gluons and bosons. It includes the key role and significance of the Higgs boson in moulding these foundational elements and giving structure to matter. It highlights how discoveries in particle physics were made and have radically changed understanding of the material universe. The book concludes by considering the implications of the discovery of the Higgs boson, and asks whether massive neutrinos might be key to resolving the mystery surrounding the absence of antimatter.
Beyond the tropicalization of concepts: theorizing digital realities with and from the Global South (introduction to a special issue)
Authors: Gómez-Cruz Edgar , Horst Heather , Siles Ignacio , Soriano Cheryll
Published: November 2023

In this introductory section of the special issue titled “Beyond the Tropicalization of Concepts: Theorizing Digital Realities With and From the Global South,” the editors present a critical examination of the unquestioned adoption of theoretical frameworks from dominant regions of power and knowledge in the context of the Global South. This process, referred to as the “tropicalization of concepts,” is scrutinized for its consequences, which include the unequal significance of concepts, the naturalization of certain realities, the one-sided flow of ideas, and their solidification in public policies. In response to these challenges, the eight articles included in this special issue contribute valuable insights into innovative approaches for studying, theorizing, and engaging with the unique digital realities of the Global South. These articles shed light on diverse aspects of digital media use in different regions and offer fresh perspectives on how to conceptualize and address the associated issues.
Effectiveness of Cerebral Embolic Protection in Transcatheter Aortic Valve Replacement with High Aortic Valve Calcium Burden
Authors: Gupta A , Koren O , Patel V , Nagasaki T , Patel D , Golwala K , Chakravarty T , Al-Jilaihawi H , Nakamura M , Makkar R
Published: November 2023

Background

The use of a cerebral embolic protection device (CEPD) during transcatheter aortic valve replacement (TAVR) has not been shown to be effective in preventing stroke in the PROTECTED-TAVR randomized controlled trial. However, whether CEPD may specifically benefit patients with high aortic valve calcium burden has not been studied.

Purpose

This study aimed to determine the effectiveness of CEPD in preventing cerebrovascular events during TAVR in patients with high aortic valve calcium scores (AVCS) (>2000 AU in men and >1300 AU in women) detected on baseline computed tomography.

Methods

We retrospectively analyzed 3505 patients who underwent transfemoral TAVR at a single center between 2016-2020 (Figure 1a). Baseline demographic, clinical, and procedural characteristics were stratified by CEPD use and AVCS (high vs. low). We performed Cox Proportional Hazards regression analysis to examine whether the use of CEPD in patients with high AVCS was associated with a lower rate of cerebrovascular events (stroke or transient ischemic attack) within 30 days (primary outcome) after adjusting for baseline characteristics.

Results

We stratified our study cohort into four subgroups: low AVCS without CEPD (n=1163), low AVCS with CEPD (n=633), high AVCS without CEPD (n=1081), and high AVCS with CEPD (n=628). Patients for whom CEPD was used in high AVCS group had lower prevalence of peripheral arterial disease compared with no CEPD use. Otherwise, there were no significant differences in the baseline characteristics between patients with and without CEPD in either the low or high AVCS subgroups (Table). In adjusted analysis, CEPD use (HR 1.30 [95% CI, 0.64-2.65)] or high AVCS (HR 1.16 [95% CI, 0.64-2.02)] were not associated with a decreased rate of primary outcome (Figure 1b).

Conclusion

This study indicates that CEPD use is not associated with lower cerebrovascular events after TAVR, even in patients with a high aortic valve calcium burden. Further research is needed to identify effective stroke prevention strategies for this patient population.Study design and Cox regression analysesBaseline Characteristics and Outcomes