bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the rate of change of thread angle and thread distance considering the interference factor under before and after the dynamic vibration of the fastening system
Authors: Chen C M , Chang H L , Chien C Y , Tsui C W
Published: November 2023

Precision nuts are widely used in tool spindles and ball screws. Proper locking gives the bearing the right amount of pre-pressure so that the inner balls can roll steadily and inhibit friction and rapid temperature rise. If no pre-pressure is given to the bearing, it will cause the inner ball to slide irregularly and generate extremely high temperatures. In this paper, the precision nuts used are the flank locking precision locked nut and clasp locking precision locked nut for Taguchi method experiments. The control factors are nut type, Fitting clearance, and lubrication oil. Interference factors are surroundings temperature, assembly personnel, and torque wrench. The purpose is to obtain more suitable anti-loosening characteristics by the Taguchi method under the influence of interference factors and to check the thread angle and thread pitch before and after the experiment. The experimental results were analyzed form Taguchi method to find the combination of parameters with the maximum S/N and the variance analysis to obtain the significant factor. Finally, the regression equation of the loosening prevention characteristics was obtained by regression analysis, which shows that the optimized parameters effectively improve the loosening prevention characteristics and explore the interference factor on the loosening prevention characteristics of precision nuts.
Optimization of the mechanical properties of machine tool with steel reinforced mineral concrete
Authors: Chuang H C , Chen C R
Published: November 2023

High damping and high static stiffness are essential to improve the static and dynamic characteristics of machine tools. Traditionally, the structural parts of machine tools are usually made of cast iron and steel, which may lead to poor surface finish and inaccurate dimensions of finished products. Therefore, many scholars have investigated other alternatives of structural material for machine tools, such as concrete, polymer concrete and epoxy granite. Although epoxy granite has better damping properties, its structural stiffness (as measured by Young’s modulus) is only 1/3 of the gray cast iron. Thus, this study would introduce several steel bar designs into epoxy granite to improve the static stiffness and quantitatively review the performance by finite element analysis. The results showed that the equivalent static stiffness and natural frequency were about 12 to 20% higher than the structural material of cast iron. Therefore, the proposed finite element model of vertical machining center (VMC) column in epoxy granite could serve as a feasible alternative to achieve higher damping or static stiffness, as it was also more environmentally friendly to the manufacturing process.
Properties of 6061 aluminum alloy treated with laser alloying
Authors: Yang Y S , Bai T , Wang T , Xie Y W , Chen H L
Published: November 2023

In this study, a laser surface alloying method is used to alloy 1.8 mm thick 6061 aluminum alloy sheets with Ni alloy powder. The mechanical properties of the resulting alloy are investigated. The experimental results show that, following laser surface alloying, a crack-free zone can be generated but some fine porosity appears. The hardness and the wear properties of the laser alloying specimens are superior to those of the Al-matrix. A hardness of 539 HV is achieved, which is five times greater than that of the Al-matrix. As a result, the laser alloying specimens exhibit excellent wear properties and higher sliding wear distances and speeds compared to those of the Al-matrix, whereby the sliding distance is greater by up to eight times and the sliding speed is increased four-fold.
Application of a novel generative adversarial network to wind power forecasting
Authors: Liao G C , Wu R C , Wu T T , Liao B T
Published: November 2023

As the global economy rapidly develops, energy consumption and carbon dioxide emissions have increased annually, prompting countries to strive for carbon neutrality by 2050. Accurate wind power forecasting can aid power system dispatch departments to obtain wind farms’ output and improve the power system’s new energy absorption capacity by coordinating multiple power generation resources. To this end, this study proposes a novel method for wind power forecasting: the Generative Adversarial Network method-based Deep Q Neural Network (GDQN). Wind power is a nonlinear model with random characteristics like dynamics and uncertainty. The GDQN generates wind power data similar to historical wind power data, solving the problem of insufficient wind power data samples by developing adversarial networks. The deep Q-learning network is then utilized to predict future wind power data. The experimental results based on the actual test of the total power generated by all wind turbines in a complete wind farm indicate that the proposed GDQN method can significantly reduce the Mean Absolute Percentage Error (MAPE %) of wind power forecasting, as compared to other commonly used methods in wind power forecasting.
Study on electrochemical supercapacitor performance of modified lavender biochar
Authors: Wang G X , Xia L S , Zhu X S , Wu J X , Liu X
Published: November 2023

In this study, we proposed a simple and low-cost method for the synthesis of heteroatom-doped porous carbons. Lavender waste residue as biomass precurso, using hydrothermal method synthesized N and S doped nano-layered porous carbon (NLPC-N/S) with high conductivity triumphantly. In the three-electrode system, NLPC-S showed an excellent capacitance (0.5A·g−1, 637.5 F·g−1) in 6 M KOH aqueous solution, which exceeded the specific capacitance of many reported biomass-derived porous carbons, and elucidated charge transfer mechanism and energy storage mechanism were both typical double-layer capacitance characteristics and pseudo-capacitance characteristics. The results of this study provide a cost-effective strategy for the recycling of biological waste, and that biomass carbon materials have high electrochemical performance potential in the field of energy storage.
Research on graphene oxide modified polymer as multifunctional filtration reducer for oil-well cementing
Authors: Xu P , Xia X J , Jin J Z , Yu Y J , Zhang J Y , Zhang H Z
Published: November 2023

Conventional filtration reducers have limited utility in cementing at deep oil and gas fields because of their poor temperature resistance and single function. As a novel multifunctional filtration reducer, graphene oxide-modified polymer GO-PADI was developed by radically copolymerizing 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N, N-dimethyl acrylamide (DMAM) and itaconic acid (IA) between graphene oxide sheets. The microstructure of GO-PADI was confirmed through the utilization of different methods such as fourier transform infrared spectroscopy (FT-IR). The performance evaluation results showed that GO-PADI had the high thermal stability, and could control filtration of cement slurry as conducted by the American Petroleum Institute (API) less than 50 mL, which is 17 % lower than that of the traditional filtration reducer PADI. GO-PADI could increase compressive strength of cement stone by 30.3 %, and decrease elastic modulus by 10.9 % in three-day curing period. GO-PADI has the multifunctional functions of reducing fluid loss, strengthening and toughening, and can effectively improve the engineering performances for high-temperature cement slurry.
A facile preparation of g-C3N4/a-Fe2O3/TiO2 composite and its photocatalysis performance on the degradation of DNT/TNT under simulated sunlight
Authors: Xiufang Qi , Yuan Li , Chunyao Song
Published: November 2023

It has been difficult to solve the environmental problems caused by trinitrotoluene(TNT)/dinitrotoluene(DNT) containing explosive wastewater for decades. The advanced oxidation method based on photocatalysis and hydrogen peroxide has gained considerable popularity in the field of pollutant degradation. In order to find a coping strategy, using a simple method involving obtaining g-C3N4/Fe2O3(CNFe) by two-step calcination and then mixing butyl titanate and CNFe through a sol-gel pathway, a type of low-cost g-C3N4/Fe2O3/TiO2(CNFeTi) ternary composite was prepared and then characterized by SEM-EDS, IR, Raman spectroscopy, XRD, XPS, UV-vis, etc. Using the prepared CNFeTi as catalyst, the effects of the amount of catalyst and H2O2 dosage on the photocatalytic degradation of DNT/TNT in aqueous solution have been investigated under simulated sunlight, with the reaction being tracked by UV-vis spectrophotometer. And from the results it was shown to have excellent photocatalytic performance. Under the conditions of 1.0 g·L−1 H2O2, 3.0 g·L−1 C3N4/Fe2O3/TiO2, 15 A current intensity of a Xenon light source and natural pH, 95% DNT and 91% TNT were removed after 30 min irradiation, indicating the proposed system has a high degradation rate. The CNFeTi catalyst could be reused at least five times and exhibited good stability.
Spherical TiAl Alloy Powders by PREP: Preparation, Microstructure and Properties
Authors: Song M , Zhang Y , Yang Y , Li Y , Yang H , Wang Y , Li Y , Zhang X
Published: November 2023

TiAl alloy powders were prepared by plasma rotate electrode pulverization (PREP) with high speed. The effect of preparation process on the microstructure and properties of powders was studied. The results showed that the titanium aluminum powder prepared by PREP method was solid and spherical without satellite powder. The powders had two morphologies: cracked surface and smooth surface. The relationship between particle size and surface morphology was as follows: the smaller the particle size, the smoother the surface. Ti, Nb and Gr elements were uniformly distributed, while Al elements were segregated, but no alloy element loss occurred. The powderswere mainly composed ofγ-TiAl and α2-Ti3Al phase and contained a small amount of NbCr2phase. The average thickness of laminates ofα2+γwas about 0.2μm. Thelamellar thickness of γ phase was about 20nm. The long axis of NbCr2phase was 200nm, and the short axis was 50 ~ 100nm. The higher the rotating speed of the electrode, the smaller the particle size and the higher the sphericity of the powders. With the increase of plasma generator current, the particle size decreased and the sphericity increased. The yield of - 100 mesh ~ + 325 mesh powders for EBSM molding could reach more than 80.68 %, when42000r / min and 670A process parameters were adopted.
Preparation process and development trend of gold conductor slurry
Authors: Zhu Jiaqing , Guan Junqing , Bao Jinxiang , He Xin
Published: November 2023

This article provides an overview of the development of electronic slurries. It summarizes the development and preparation processes of the various components of traditional gold conductor slurries, as well as the process flow for mixing each component to prepare the gold slurries. Then, it analyzes the problems in the development of the domestic gold slurry industry and makes a certain degree of prediction for the future development trend of gold conductor slurries based on the development of the entire industry.
Tensile Properties of DD15 Single Crystal Superalloy at Different Temperature
Authors: Shi Z X , Liu S Z , Zhao J Q
Published: November 2023

DD15 single crystal nickel-based alloy was prepared by a directional solidification induction heating furnace and its tensile properties were investigated at the 23°C, 400°C, 800 °C, 1100°C and 1140°C. The tensile fracture mechanism of the alloy at different temperature was investigated. Results indicate that tensile strength of the alloy reduces first, increases afterward, and decrease sharply at last as the test temperature rises, while the tensile plasticity exhibit the reverse change trend. The extension strength of the alloy is superior to that of EPM-102 alloy. At 23°C, 400°C and 800°C, the tensile fracture mode of the alloy is quasi-cleavage mechanism, and at 1100°C and 1140°C that is dimple model. As tensile fracture at 23°C, 400°C and 800°C, the γ′ precipitate nearly keeps cube shape, while that becomes rectangular after tensile fracture at 1100°C and 1140°C. The APB and stacking fault can be seen in the γ′ phase at 23°C, 400°C and 800°C. There is dislocation networks at the γ/γ′ interface and the deformation characteristic is dislocation by-passing mechanism at 1100°C and 1140°C.
Surface precipitate analysis of gas atomized Ni-Base superalloy powders
Authors: Liu Y F , Zhang L C , Xu W Y , Liu N , Yuan H , Fan X S , Wang S X , Shen J K , Li Z , Zhang G Q
Published: November 2023

Powders surface precipitate has strong relations with the microstructure and properties of powder metallurgy components. Morphology, element distribution and crystal structure of the precipitate at gas atomized Ni-base superalloy powders surface were investigated. Results show that the precipitate is lamelliform and prefers to form at grain boundaries and interdendrite regions than dendrite arms. With powders size decreasing, the precipitate shape observed from surface varies from strip to rectangular and to nearly round, and the precipitate density increases, measured 17.75 μm−2, 21.42 μm−2, 26.50 μm−2 at nearly 45μm, 30μm and 10μm powders surface respectively, but the precipitate average size changes conversely, that is 228nm, 193nm, 77nm respectively. The precipitate enriches in high melting point elements Ti, Nb, Mo, W, Zr and poor in low melting point elements Ni, Cr, Co, Al. Crystal structure analysis reveals that the precipitate is MC, M23C6 or M6C carbide.
Space radiation environment adaptability of the domestic 5056 high-performance aluminum honeycomb
Authors: Wu Haisheng , Liu Baorong , Wang Xiangke , Xu Ting , Wei Yuxuan , Jin Nan , Yu Shuai , Lv Qi , He Cheng
Published: November 2023

In order to investigate the influence of space radiation environment on the performance of domestic 5056 high-performance aluminum honeycomb core, the effects of different irradiation effects and different radiation doses on the nodal strength and mechanical properties of domestic 5056 high-performance aluminum honeycomb core were studied through space radiation environmental tests and mechanical property tests such as high-energy electron irradiation, γ-ray irradiation, ultraviolet irradiation, hot and cold shock test, vacuum volatilization test. The results show that under multiple environmental conditions such as high-energy electron irradiation γ-ray irradiation, ultraviolet irradiation, and hot and cold shock environment, the domestic high-performance aluminum honeycomb core shows excellent adaptability to the irradiation environment and can be used for a long time in the extravehicular environment. However, when the radiation dose is greater than 2 × 109rad, the strength of honeycomb core nodes decreased significantly. The vacuum volatilization test results sindicate that the material meets the gas requirements of aerospace raw materials and has extremely low vacuum pollution characteristics.
Deterioration mechanism of sulfoaluminate concrete at high temperature
Authors: Duan Denghui , Chen Jiajian
Published: November 2023

In order to explore the deterioration law and mechanism of sulfoaluminate concrete under high temperature environment, this paper studied the deterioration law of sulfoaluminate concrete by observing the crack changes of sulfoaluminate concrete samples under different water/cement ratio, different ages and different temperatures after experiencing different high temperatures, and measuring the residual mass ratio, infrared temperature rise, ultrasonic pulse speed and compressive strength. The results show that the loss of strength and mass is the fastest when the temperature of sulfoaluminate concrete is 200 °C, and the loss of strength and mass becomes slower and slower with the increase in temperature. The main reasons for the deterioration of sulfoaluminate concrete are the destruction of microstructure by ettringite and Ca(OH)2 by dehydration at high temperature. The higher the initial strength of sulfoaluminate concrete, the greater the strength loss after high temperature, but the higher the residual strength.
Effect of second-step austempering temperature on mechanical damping of austempered ductile iron
Authors: Zhang Y , Cuo E , Wang L , Feng Y , Zhao S , Liu X , Yi P
Published: November 2023

Austempered ductile iron(ADI) has good strength and toughness, which is widely used in aerospace, engineering machinery and automobile manufacturing. In the above application fields, the requirements of safety and comfort are gradually increasing, so ADI is required not only to have excellent mechanical properties, but also to have high damping properties. The performance of ADI is closely related to its heat treatment method. Therefore, it provides a theoretical basis for the application of ADI, and reveals its mechanism to some extent. The influence of two-step ADI’s mechanical properties and damping properties due to two-step austempering quenching temperature is the main content of this paper. The retained austenite with obvious coarsening of bundle ferrite and increased size is the experimental result obtained after the increase of austempering temperature in the second step. After that, when the austempering temperature in the second step increases, the retained austenite content will directly decrease. The tensile strength of ADI will increase first and then decrease with the increase of austempering temperature in the second step. And the value reaches the maximum of 1350MPa at 360°C. The yield strength of ADI, which reaches the maximum value (1252MPa) at 400 °C, will follow the increase of austempering temperature in the second step, and the elongation and impact energy of ADI will gradually decrease. The elongation and impact energy of ADI will gradually decrease with the increase of austempering temperature in the second step. The minimum values of 4.8% and 42J are obtained when the austempering temperature in the second step reaches 400 °C. The impact fracture morphology shows that the fracture mechanism will change from ductile fracture to brittle fracture with the increase of austempering temperature in the second step. The reason why the internal friction value (Q−1) of ADI with different austempering temperatures in the second step increases gradually is the increase of strain amplitude. There are obvious S-K peaks and Ge peaks, that is, the damping characteristics change with frequency.
On the crashworthiness of aperiodic chiral mechanical metamaterials: design and modeling method
Authors: Xu Weiyun , Zhang Hanyu , Liu Zhao , Zhu Ping
Published: November 2023

Chiral mechanical metamaterial has become topical in energy absorption for the unusual compression-to-twist deformation determined by the asymmetric chirality geometry of their microstructures. However, the insufficient research on the dynamic crash behavior with high nonlinearity and the lack of efficient design and modeling method have blocked the development of chiral mechanical metamaterials considering crashworthiness. In this work, the structure-property relationship of chiral mechanical metamaterials under medium-strain-rate impact was systematically investigated. We proposed an aperiodic framework considering additive manufacturing which enabled both the ordered and disordered chiral mechanical metamaterials utilizing a screw-theory-based assembly rule. The strut components had variable cross-sections and the joints were fillet-enhanced in order to improve the compressive performance. Meanwhile, the corresponding efficient modeling method for finite element analysis (FEA) was introduced. The constitutive relation, damage criteria, and damage revolution of the 316L stainless steel were established considering strain rate effect. Finally, the deformation mechanisms and energy absorbing capabilities of the proposed chiral mechanical metamaterials were demonstrated and discussed based on the mechanical behaviors and the proposed chirality indexes. The numerical results indicated that the proposed design and modeling method provided an effective paradigm for the crashworthiness design of light-weight materials and structures, facilitating the further applications in fields of automobile, civil engineering, aerospace, etc.
Microstructure, mechanical properties, and energetic characteristics of novel peritectic W
x
NbTiZr medium entropy alloys
Authors: Shen Z D , Ma Z L , Cheng X W
Published: November 2023

Novel W
x
NbTiZr medium entropy alloys (MEAs) with tungsten concentrations of 15–25 at.% were produced using arc vacuum melting. The microstructure formation, mechanical behaviours and energetic characteristics were studied. Peritectic reaction occurs in these alloys, resulting in BCC1 and BCC2 phases with close lattice parameters, along with unique pearl chain structures. The average grain sizes of these alloys are less than 10 μm. W0.75NbTiZr alloy exhibited the most significant grain refinement, resulting in a remarkable combination of strength and ductility. When subjected to high-speed impact, the W
x
NbTiZr projectiles reacted with air and release high amounts of energy. These W
x
NbTiZr MEAs exhibit high density, exceptional mechanical properties, and significant energy release, showcasing their immense potential as high-strength energetic structural materials
Research status of phase change memory and its materials
Authors: Yang Peng , Lyu Baoguo , Ding Zhaochong , Luo Junfeng , He Jinjiang
Published: November 2023

Phase change memory technology is a new technology in non-volatile memory technology. Phase change memory technology has many advantages, such as non-volatility, high reading and writing speeds, better data retention, and strong compatibility with CMOS technology, and has been paid attention to by many researchers. Phase change materials are mainly chalcogenide compound materials. Researchers have done a lot of research on Ge-Sb-Te, Ge-Te, and Sb-Te-based phase change materials and developed some new phase change material systems. In addition, researchers have carried out in-depth research on the phase transition mechanism, but the existing atomic umbrella jump theory, multiple ring theory, resonance bond theory, octahedral structure theory, etc. have not formed a unified understanding of the phase transition mechanism. At present, phase change memory is mainly prepared by magnetron sputtering of phase change material targets, which results in fast deposition and high purity of the prepared film. In this paper, based on the development of phase change storage materials, the system of phase change materials and its phase change mechanism, the phase transition mechanism of phase change memory, the preparation and characterization methods of phase change films, the industrialization progress, and other research work are reviewed.
An Investigation into the Factors and Mechanisms Underlying Corrosion Failure of B10 Copper Tubes in Shipboard Pipelines
Authors: Li Guo , Wenlong Chen , Qiuling Huang , Sichong Jian , Peng Zhou , Lianhua Liu
Published: November 2023

The present study investigated the corrosion behavior and mechanism of B10 copper tubes used for shipboard pipelines through various analytical techniques, including macroscopic inspection, chemical analysis, electrochemical impedance, corrosion product morphology, and physical phase and electron microscopic observation. The research findings revealed that the surface corrosion product film on the B10 copper tube in seawater mainly consists of Cu2O. Furthermore, the corrosion behavior under actual working conditions was attributed to crevice corrosion, non-electric coupling corrosion, and the corrosion mechanism was found to be the result of the combined effect of oxygen concentration difference cell and occlusion cell autocatalytic effect. These observations provide valuable insights into the corrosion performance of B10 copper tubes in seawater, which could potentially aid in improving their durability and reliability in marine applications.
Fracture failure analysis of the main shaft of a large sewage treatment equipment
Authors: Wang Kun , Feng Chun , Zhu Lijuan , Wang Xinhu
Published: November 2023

In view of the main shaft fracture failure accident occurred in the service process of a sewage treatment equipment, this paper carried out the fracture macro analysis, chemical composition analysis, material mechanical properties testing, metallographic structure analysis, fracture micro morphology analysis of the failure of the main shaft. The analysis results show that there are cold cracks in the weld and toe of the main shaft of the equipment, and the cracks expand under the action of rotating and bending alternating loads. The main shaft speed of the equipment is 3r/min, the load change frequency is very small, and the corrosive medium has sufficient time to play a role in the crack tip, fatigue cracks further propagated, leading to corrosion fatigue fracture of the main shaft. So in order to prevent this kind of failure, it is suggested to improve the welding process regulations for the equipment of the main shaft and rationally select welding materials.
Research on micro strain and sub grain size of each texture in 6A16 Al sheet
Authors: Shuming Wang , Baiqing Xiong , Pu Li , Zhihui Li , Xiwu Li
Published: November 2023

The micro strain and sub grain size of each texture type in cold rolled 6A16 Al alloy sheet were calculated using X-ray line broadening method, and the effects on the texture transformation during recrystallization process were investigated. The results showed that strain in R/S was the largest, and Brass, Copper, Goss in sequence, the sub grain size in R/S was the least, and Brass, Goss, Copper in sequence, which was coincident with the texture transformation speed during solid solution process, meanwhile, the contents of recrystallization texture, such as R/S, Cube and CubeND20 reduced obviously as the cold rolling stored energy released when recovery process imported before solid solution. It was conformed that the recrystallization texture transforming was influenced by stored energy significantly.
Application and research of titanium alloy oil drill pipes
Authors: Ma Dong , Zhu Shidong , Zhang Kai , Zhu Lijuan , Zhou Yang
Published: November 2023

The complex and harsh drilling environment has put forward higher requirements and standards for future drilling tools. Compared with other drill pipes, titanium alloy drill pipe has a series of characteristics such as high specific strength, excellent corrosion resistance, fatigue resistance, and non-magnetic, making it be the first choice of material for oil and gas drilling in unconventional deep well, deep sea and other harsh environments. This paper discussed the design and microstructure properties of titanium alloy drill pipes in terms of alloy composition, service performance as well as pipe body processing and joint connection. Combined with the development of the application and standards of titanium alloy drill pipe, the prospects of the development and application of titanium alloy drill pipe in unconventional drilling operations such as deep wells and ultra-deep wells were foreseen, in order to provide support for promoting the application and development of titanium alloy drill pipe in the oil fields.
Process Analysis of DLP Photocuring 3D Printing with Modified High-strength Resin
Authors: Sang Jian , Jiang Kai , Li Rui , Xu Gui-Long , Zhao Xin-Xin , Gao Chen , Wei Zi-Zhong
Published: November 2023

The excellent properties of graphene oxide, along with its dispersibility and hydrophilicity, make it suitable for blending with other substrates to obtain reinforcements. In this paper, high-strength photosensitive resin is mixed with graphene oxide to obtain reinforced photosensitive resin. The impact of different mass fractions of graphene oxide on the appearance, dimensional accuracy, bending strength, tensile strength, and fracture morphology of printed samples is investigated using DLP surface molding 3D printing technology. As the mass fraction of graphene oxide increases, the size error of the printed sample decreases, while the bending strength and tensile strength increase, indicating a favorable bonding effect. However, when the mass fraction of graphene oxide exceeds 0.6%, the bonding between the two materials becomes poorer, leading to the opposite outcome. The hierarchical influence of different parameters on the tensile strength of mixed-material DLP printed samples can be summarized as follows: graphene oxide content exhibits the strongest influence, followed by layer thickness, exposure time, and exposure intensity.
Pipeline Internal Surface Detection based on Convolutional Neural Networks and Code Wave Time-Frequency Transform
Authors: Xue Xianwen , Chen Bowei , Jiang Hao , Li Mengyuan
Published: November 2023

This study introduces an innovative approach that integrates principles of coda wave interferometry, wavelet transform, convolutional neural networks, and deep learning for the analysis and detection of contaminants within pipelines. The primary objective of this method is to identify various types of contaminants, enhance contamination detection sensitivity and accuracy, thereby providing an effective solution for monitoring and remediation in the oil and gas pipeline transportation industry. The findings of this research offer valuable insights and serve as a significant reference for improving pipeline cleaning practices. Further optimization can be explored through enhancements in the model architecture, the incorporation of data augmentation techniques, and the exploration of alternative training strategies. However, the performance of this method still requires further study and improvement. The study encompasses the following key aspects: Firstly, ultrasonic analysis is employed to characterize the structural properties of contaminants, enabling the extraction of crucial structural features and performance parameters through the analysis of ultrasonic echo signals. Secondly, wavelet transform is applied to conduct comprehensive time-frequency analysis of the ultrasonic echo signals, facilitating the capture of distinctive features associated with contaminants across different frequency bands and time scales. Thirdly, convolutional neural networks, specifically leveraging the VGG-16 model, are used to extract informative features from the ultrasonic signals and perform classification. Through rigorous training and fine-tuning processes, the model achieves precise identification of contaminant types and estimation of their thickness.
Effect of low dose irradiation of heavy ion on electrochemical corrosion and IASCC behavior of austenitic steel
Authors: Gao Junxuan , Cao Han , Li Dongxing , Fan Yu , Zhang Peng , Zheng Quan , Zhong Weihua
Published: November 2023

The impacts of low dose irradiation on the behavior of electrochemical corrosion and irradiation assisted stress corrosion cracking for 321 stainless steel were studied using Fe2+ ion irradiation to simulate neutron radiation damage in primary circuit environment of pressurized water reactor. Low dose irradiation can improve the pitting resistance and reduce the cracking tendency of the alloy in B-Li solution to a certain extent, which was related to the δ phase content on the near-surface of the sample: The higher δ phase content on the near-surface of the 2 dpa irradiated sample was observed by grazing incident X-ray diffraction. In addition, the pits was significantly increased near micro-cracks for the unirradiated sample, indicating that the existence of pits induced the initiation of cracks. The research results provided an important reference for the failure mechanism of irradiation assisted stress corrosion cracking of core components.
Analysis of electrical performance and assessment of aging state for retired high-voltage cable accessory insulation
Authors: Yu Shihu , Yu Xin , Peng Xiangyang , Fan Yazhou , Chen Yikai , Zeng Xin , Wang Haozhou , Chen Shuyu , Ren Chengyan
Published: November 2023

The cable accessories constitute a vulnerable element and are prone to failures in the operation of power transmission lines. To investigate the changes in the electrical performance and aging state of high-voltage cable accessories with different operating time, the volume resistivity, breakdown electric field, dielectric constant, and trap parameters of insulation samples taken from retired cable accessories were characterized. The results indicate that there is a certain correlation between the macroscopic dielectric characteristics of cable accessory insulation and its aging state. With the increase of operating time, the volume resistivity and breakdown electric field decrease, while the dielectric constant initially increases and then decreases. The trap distribution of cable accessory insulation can effectively reflect its aging state. With the increase of operating time, the trap energy levels of the accessory insulation become shallower, and the trap density increases. The trap results of the accessory insulation show good consistency with the resistivity and breakdown field strength. Clustering analysis is also used to classify the test data, and the results validate that the trap energy levels and trap density of the insulation samples have better correlation with the insulation aging state of cable accessories than macroscopic dielectric parameters.
Phase field simulating grain refinement of magnesium alloy by thin strip second phase particles
Authors: Zhao Daowen , Wu Yan , Xiong Jinlin
Published: November 2023

The study has investigated the grain growth of AZ31 magnesium alloy matrix with fine strip second phase particles, by the phase field model in the real space and time, through introducing free energy equation, and compared with the simulated results containing spherical particles. The results showed that both the thin strip ellipsoidal particles and the cuboid particles have grain refinement effect on the microstructure, moreover, when the content of the second phase particles is the same, the refining effect of thin strip particles could be better than the spherical particles on the matrix microstructure. This study provides the real scale phase field models to research the grain refinement by second phase particles.
Design of Nupix-A2, a Monolithic Active Pixel Sensor for heavy-ion physics
Authors: Huang J. , He R. , Niu X. , Han W. , Yin R. , Wang Q. , Liao J. , Yang P. , Zhou W. , Tian Y. , Wang Y. , Fu F. , Cao B. , Yang H. , Zhang H. , Liao S. , Li X. , Zhao C.
Published: November 2023

The High Intensity heavy-ion Accelerator Facility (HIAF) is being constructed to generate intense beams of primary and radioactive ion for a wide range of research fields. Hence, a Monolithic Active Pixel Sensor (MAPS) named Nupix-A2 has been developed in a 130-nm High Resistivity CMOS process. The Nupix-A2 can simultaneously measure the particle hit' energy, arrival time, and position. It consists of a 128 × 128 pixel array, a digital-to-analog converter array, and a digital control module. The Nupix-A2 can measure energy deposition from 300 e- to over 50 ke- and time duration from 13 μs to 140 μs. This sensor also offers full readout mode and fast readout mode. In full-readout mode, all pixels measure arrival time and energy, suitable for real-time beam monitoring and image reconstruction. In fast-readout mode, only particle hit's positions are detected and read out. This paper presents the design of the Nupix-A2.
If you build it, will they come? Insect community responses to habitat establishment at solar energy facilities in Minnesota, USA
Authors: Walston Leroy J , Hartmann Heidi M , Fox Laura , Macknick Jordan , McCall James , Janski Jake , Jenkins Lauren
Published: November 2023

Global declines in insect populations have important implications for biodiversity and food security. To offset these declines, habitat restoration and enhancement in agricultural landscapes could mutually safeguard insect populations and their pollination services for crop production. The expansion of utility-scale solar energy development in agricultural landscapes presents an opportunity for the dual use of the land for energy production and biodiversity conservation through the establishment of grasses and forbs planted among and between the photovoltaic solar arrays (‘solar-pollinator habitat’). We conducted a longitudinal field study across 5 years (2018–2022) to understand how insect communities responded to newly established habitat on solar energy facilities in agricultural landscapes by evaluating (1) temporal changes in flowering plant abundance and diversity; (2) temporal changes in insect abundance and diversity; and (3) the pollination services of solar-pollinator habitat by comparing pollinator visitation to agricultural fields near solar-pollinator habitat with other agricultural field locations. We found increases over time for all habitat and biodiversity metrics: floral rank, flowering plant species richness, insect group diversity, native bee abundance, and total insect abundance, with the most noticeable temporal increases in native bee abundance. We also found positive effects of proximity to solar-pollinator habitat on bee visitation to nearby soybean (Glycine max) fields. Bee visitation to soybean flowers adjacent to solar-pollinator habitat were comparable to bee visitation to soybeans adjacent to grassland areas enrolled in the Conservation Reserve Program, and greater than bee visitation to soybean field interior and roadside soybean flowers. Our observations highlight the relatively rapid (<4 year) insect community responses to grassland restoration activities and provide support for solar-pollinator habitat as a feasible conservation practice to safeguard biodiversity and increase food security in agricultural landscapes.
Widespread deepening of the active layer in northern permafrost regions from 2003 to 2020
Authors: Liu Zhihua , Kimball John S , Ballantyne Ashley , Watts Jennifer D , Natali Susan M , Rogers Brendan M , Yi Yonghong , Klene Anna E , Moghaddam Mahta , Du Jinyang , Zona Donatella
Published: November 2023

The changing thermal state of permafrost is an important indicator of climate change in northern high latitude ecosystems. The seasonally thawed soil active layer thickness (ALT) overlying permafrost may be deepening as a consequence of enhanced polar warming and widespread permafrost thaw in northern permafrost regions (NPRs). The associated increase in ALT may have cascading effects on ecological and hydrological processes that impact climate feedback. However, past NPR studies have only provided a limited understanding of the spatially continuous patterns and trends of ALT due to a lack of long-term high spatial resolution ALT data across the NPR. Using a suite of observational biophysical variables and machine learning (ML) techniques trained with available in situ ALT network measurements (n = 2966 site-years), we produced annual estimates of ALT at 1 km resolution over the NPR from 2003 to 2020. Our ML-derived ALT dataset showed high accuracy (R
2 = 0.97) and low bias when compared with in situ ALT observations. We found the ALT distribution to be most strongly affected by local soil properties, followed by topographic elevation and land surface temperatures. Pair-wise site-level evaluation between our data-driven ALT with Circumpolar Active Layer Monitoring data indicated that about 80% of sites had a deepening ALT trend from 2003 to 2020. Based on our long-term gridded ALT data, about 65% of the NPR showed a deepening ALT trend, while the entire NPR showed a mean deepening trend of 0.11 ± 0.35 cm yr−1 [25%–75% quantile: (−0.035, 0.204) cm yr−1]. The estimated ALT trends were also sensitive to fire disturbance. Our new gridded ALT product provides an observationally constrained, updated understanding of the progression of thawing and the thermal state of permafrost in the NPR, as well as the underlying environmental drivers of these trends.
A top-down estimation of subnational CO2 budget using a global high-resolution inverse model with data from regional surface networks
Authors: Nayagam Lorna , Maksyutov Shamil , Oda Tomohiro , Janardanan Rajesh , Trisolino Pamela , Zeng Jiye , Kaiser Johannes W , Matsunaga Tsuneo
Published: November 2023

Top-down approaches, such as atmospheric inversions, are a promising tool for evaluating emission estimates based on activity-data. In particular, there is a need to examine carbon budgets at subnational scales (e.g. state/province), since this is where the climate mitigation policies occur. In this study, the subnational scale anthropogenic CO2 emissions are estimated using a high-resolution global CO2 inverse model. The approach is distinctive with the use of continuous atmospheric measurements from regional/urban networks along with background monitoring data for the period 2015–2019 in global inversion. The measurements from several urban areas of the U.S., Europe and Japan, together with recent high-resolution emission inventories and data-driven flux datasets were utilized to estimate the fossil emissions across the urban areas of the world. By jointly optimizing fossil fuel and natural fluxes, the model is able to contribute additional information to the evaluation of province–scale emissions, provided that sufficient regional network observations are available. The fossil CO2 emission estimates over the U.S. states such as Indiana, Massachusetts, Connecticut, New York, Virginia and Maryland were found to have a reasonable agreement with the Environmental Protection Agency (EPA) inventory, and the model corrects the emissions substantially towards the EPA estimates for California and Indiana. The emission estimates over the United Kingdom, France and Germany are comparable with the regional inventory TNO–CAMS. We evaluated model estimates using independent aircraft observations, while comparison with the CarbonTracker model fluxes confirms ability to represent the biospheric fluxes. This study highlights the potential of the newly developed inverse modeling system to utilize the atmospheric data collected from the regional networks and other observation platforms for further enhancing the ability to perform top-down carbon budget assessment at subnational scales and support the monitoring and mitigation of greenhouse gas emissions.
Positive Hamiltonians cannot give exponential decay of positive observables
Authors: Facchi Paolo , Lonigro Davide
Published: November 2023

The survival probability of a quantum system with a finite ground energy is known to decay subexponentially at large times. Here we show that, under the same assumption, the average value of any quantum observable, whenever well-defined, cannot converge exponentially to an extremal value of the spectrum of the observable. Large-time deviations from the exponential decay are therefore a general feature of quantum systems. As a simple application of these results, we show that, when considering an open quantum system whose dynamics is generated by a Hamiltonian with a finite ground energy, a large-time exponential decay of populations is forbidden, whereas coherences may still decay exponentially.
Absence of logarithmic enhancement in the entanglement scaling of free fermions on folded cubes
Authors: Bernard Pierre-Antoine , Mann Zachary , Parez Gilles , Vinet Luc
Published: November 2023

This study investigates the scaling behavior of the ground-state entanglement entropy in a model of free fermions on folded cubes. An analytical expression is derived in the large-diameter limit, revealing a strict adherence to the area law. The absence of the logarithmic enhancement expected for free fermions is explained using a decomposition of folded cubes in chains based on its Terwilliger algebra and

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. The entanglement Hamiltonian and its relation to Heun operators are also investigated.
Attaining the maximum Bose–Einstein condensation in a finite-size hard-core boson model
Authors: Ríos Elías , Schneider David M , Capuzzi Pablo , Alcoba Diego R , Oña Ofelia B , Torre Alicia , Lain Luis
Published: November 2023

We propose a model for hard-core bosons in a lattice which allows to achieve the optimal occupation number predicted by Tennie et al (2017 Phys. Rev. B
96 064502) for a finite number of sites. The model is based on an extension of the Hamiltonian of the so-called Hubbard star, whose quantum properties are studied by means of quantum information descriptors such as the von Neumann entropy and the mutual information. These metrics are analyzed as a function of the one- and two-particle reduced density matrices, allowing to explore the relationship between condensation and entanglement by means of a control parameter that, under a given limit, connects our findings with previous results. All developments comprised in this article have been derived by analytical methods.
First results of CO2 dispersion interferometer on EAST tokamak
Authors: LIU 刘 Yuyang 郁阳 , LI 李 Weiming 维明 , YAO 姚 Yuan 远 , ZHANG 张 Yao 耀 , ZHANG 张 Jiamin 家敏 , LIAN 连 Hui 辉 , HONG 洪 Bo 博 , WANG 王 Shouxin 守信 , JIE 揭 Yinxian 银先 , LIU 刘 Haiqing 海庆
Published: November 2023

A dispersion interferometer (DI) has been installed and operates on the Experimental Advanced Superconducting Tokamak (EAST). This DI system utilizes a continuous-wave 9.3 μm CO2 laser source to measure line-averaged electron densities accurately. In contrast to conventional interferometers, the DI does not require substantial vibration isolations or compensating systems to reduce the impact of vibrations in the optical path. It also employs a ratio of modulation amplitudes, ensuring it remains immune to the variations in detected intensities. Without a variation compensation system, the DI system on EAST reaches a density resolution of less than 1.8 × 10−2π rad and a temporal resolution of 20 μs. The measurements made by the POlarimeter-INTerferometer (POINT) system and the far-infrared hydrogen cyanide (HCN) interferometer are remarkably consistent with the DI’s results. The possibility of fringe jumps and the impact of refraction in high-density discharge can be significantly decreased using a shorter wavelength laser source. A rapid density change of 3 × 1019 m−3 during 0.15 s has been measured accurately in shot No. 114755 of EAST. Additionally, the DI system demonstrates dependability and stability under 305 s long-pulse discharges in shot No. 122054.
Who was Horace?
Authors: Morgan Llewelyn
Published: November 2023

This chapter illustrates Horace’s extensive influence on the modern world before offering a succinct narrative of his life, the son of an ex-slave who somehow managed to enjoy the best education available in Rome, culminating in ‘higher education’ in Athens—where, however, contemporary upheavals caught up with him in the shape of Marcus Brutus, the assassin of Julius Caesar. Horace joined Brutus’ army and experienced the brutal conflict at Philippi, before returning to Rome with clipped wings and embarking on his poetic career. Remarks follow on the traditional character of Roman poetry, and also the inherent alienness to modern sensibilities of important aspects of Horace’s poetry. This poet was adopted as something approaching the voice of modern Europe, yet he originated in a culture fundamentally different from those modern societies.
Epodes
Authors: Morgan Llewelyn
Published: November 2023

This chapter explains the nature of the ‘iambic’ poetry in the Epodes, a poetry of abuse with models in the Greek poets Hipponax and especially Archilochus (the latter in the 7th century bce). The association of iambic poetry with the symposium, a Greek male social gathering, is considered, and its aggressive representation of women: the point is made how selective a reading of Horace is required to produce the model of middle-aged poise and wisdom that is his modern reputation. But the high capacity of this poetry to convey the tense and febrile conditions of Rome at the time of its publication, in the immediate context of the critical battle of Actium, is also observed.